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Sample records for relative stability order

  1. Stability analysis of distributed order fractional chen system.

    Science.gov (United States)

    Aminikhah, H; Refahi Sheikhani, A; Rezazadeh, H

    2013-01-01

    We first investigate sufficient and necessary conditions of stability of nonlinear distributed order fractional system and then we generalize the integer-order Chen system into the distributed order fractional domain. Based on the asymptotic stability theory of nonlinear distributed order fractional systems, the stability of distributed order fractional Chen system is discussed. In addition, we have found that chaos exists in the double fractional order Chen system. Numerical solutions are used to verify the analytical results.

  2. Stability Analysis of Distributed Order Fractional Chen System

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    Aminikhah, H.; Refahi Sheikhani, A.; Rezazadeh, H.

    2013-01-01

    We first investigate sufficient and necessary conditions of stability of nonlinear distributed order fractional system and then we generalize the integer-order Chen system into the distributed order fractional domain. Based on the asymptotic stability theory of nonlinear distributed order fractional systems, the stability of distributed order fractional Chen system is discussed. In addition, we have found that chaos exists in the double fractional order Chen system. Numerical solutions are used to verify the analytical results. PMID:24489508

  3. Stability Analysis of Fractional-Order Nonlinear Systems with Delay

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    Yu Wang

    2014-01-01

    Full Text Available Stability analysis of fractional-order nonlinear systems with delay is studied. We propose the definition of Mittag-Leffler stability of time-delay system and introduce the fractional Lyapunov direct method by using properties of Mittag-Leffler function and Laplace transform. Then some new sufficient conditions ensuring asymptotical stability of fractional-order nonlinear system with delay are proposed firstly. And the application of Riemann-Liouville fractional-order systems is extended by the fractional comparison principle and the Caputo fractional-order systems. Numerical simulations of an example demonstrate the universality and the effectiveness of the proposed method.

  4. Dynamical stability of the holographic system with two competing orders

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    Du, Yiqiang [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); Lan, Shan-Quan [Department of Physics, Beijing Normal University,Beijing 100875 (China); Tian, Yu [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); State Key Laboratory of Theoretical Physics,Institute of Theoretical Physics, Chinese Academy of Science,Beijing 100190 (China); Zhang, Hongbao [Department of Physics, Beijing Normal University,Beijing 100875 (China); Theoretische Natuurkunde, Vrije Universiteit Brussel and The International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium)

    2016-01-04

    We investigate the dynamical stability of the holographic system with two order parameters, which exhibits competition and coexistence of condensations. In the linear regime, we have developed the gauge dependent formalism to calculate the quasi-normal modes by gauge fixing, which turns out be considerably convenient. Furthermore, by giving different Gaussian wave packets as perturbations at the initial time, we numerically evolve the full nonlinear system until it arrives at the final equilibrium state. Our results show that the dynamical stability is consistent with the thermodynamical stability. Interestingly, the dynamical evolution, as well as the quasi-normal modes, shows that the relaxation time of this model is generically much longer than the simplest holographic system. We also find that the late time behavior can be well captured by the lowest lying quasi-normal modes except for the non-vanishing order towards the single ordered phase. To our knowledge, this exception is the first counter example to the general belief that the late time behavior towards a final stable state can be captured by the lowest lying quasi-normal modes. In particular, a double relation is found for this exception in certain cases.

  5. Order-2 Stability Analysis of Particle Swarm Optimization.

    Science.gov (United States)

    Liu, Qunfeng

    2015-01-01

    Several stability analyses and stable regions of particle swarm optimization (PSO) have been proposed before. The assumption of stagnation and different definitions of stability are adopted in these analyses. In this paper, the order-2 stability of PSO is analyzed based on a weak stagnation assumption. A new definition of stability is proposed and an order-2 stable region is obtained. Several existing stable analyses for canonical PSO are compared, especially their definitions of stability and the corresponding stable regions. It is shown that the classical stagnation assumption is too strict and not necessary. Moreover, among all these definitions of stability, it is shown that our definition requires the weakest conditions, and additional conditions bring no benefit. Finally, numerical experiments are reported to show that the obtained stable region is meaningful. A new parameter combination of PSO is also shown to be good, even better than some known best parameter combinations.

  6. Optimal explicit strong stability preserving Runge–Kutta methods with high linear order and optimal nonlinear order

    KAUST Repository

    Gottlieb, Sigal

    2015-04-10

    High order spatial discretizations with monotonicity properties are often desirable for the solution of hyperbolic PDEs. These methods can advantageously be coupled with high order strong stability preserving time discretizations. The search for high order strong stability time-stepping methods with large allowable strong stability coefficient has been an active area of research over the last two decades. This research has shown that explicit SSP Runge-Kutta methods exist only up to fourth order. However, if we restrict ourselves to solving only linear autonomous problems, the order conditions simplify and this order barrier is lifted: explicit SSP Runge-Kutta methods of any linear order exist. These methods reduce to second order when applied to nonlinear problems. In the current work we aim to find explicit SSP Runge-Kutta methods with large allowable time-step, that feature high linear order and simultaneously have the optimal fourth order nonlinear order. These methods have strong stability coefficients that approach those of the linear methods as the number of stages and the linear order is increased. This work shows that when a high linear order method is desired, it may still be worthwhile to use methods with higher nonlinear order.

  7. Robust Stabilization of Fractional-Order Systems with Interval Uncertainties via Fractional-Order Controllers

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    Mohammadtaghi Hamidi Beheshti

    2010-01-01

    Full Text Available We propose a fractional-order controller to stabilize unstable fractional-order open-loop systems with interval uncertainty whereas one does not need to change the poles of the closed-loop system in the proposed method. For this, we will use the robust stability theory of Fractional-Order Linear Time Invariant (FO-LTI systems. To determine the control parameters, one needs only a little knowledge about the plant and therefore, the proposed controller is a suitable choice in the control of interval nonlinear systems and especially in fractional-order chaotic systems. Finally numerical simulations are presented to show the effectiveness of the proposed controller.

  8. Robust Stabilization of Fractional-Order Systems with Interval Uncertainties via Fractional-Order Controllers

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    Sayyad Delshad Saleh

    2010-01-01

    Full Text Available Abstract We propose a fractional-order controller to stabilize unstable fractional-order open-loop systems with interval uncertainty whereas one does not need to change the poles of the closed-loop system in the proposed method. For this, we will use the robust stability theory of Fractional-Order Linear Time Invariant (FO-LTI systems. To determine the control parameters, one needs only a little knowledge about the plant and therefore, the proposed controller is a suitable choice in the control of interval nonlinear systems and especially in fractional-order chaotic systems. Finally numerical simulations are presented to show the effectiveness of the proposed controller.

  9. Time-Discrete Higher-Order ALE Formulations: Stability

    KAUST Repository

    Bonito, Andrea; Kyza, Irene; Nochetto, Ricardo H.

    2013-01-01

    on the stability of the PDE but may influence that of a discrete scheme. We examine this critical issue for higher-order time stepping without space discretization. We propose time-discrete discontinuous Galerkin (dG) numerical schemes of any order for a time

  10. Robust Stability and Stabilization of Interval Uncertain Descriptor Fractional-Order Systems with the Fractional-Order α: The 1≤α<2 Case

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    Yuanhua Li

    2015-01-01

    Full Text Available Stability and stabilization of fractional-order interval system is investigated. By adding parameters to linear matrix inequalities, necessary and sufficient conditions for stability and stabilization of the system are obtained. The results on stability check for uncertain FO-LTI systems with interval coefficients of dimension n only need to solve one 4n-by-4n LMI. Numerical examples are presented to shown the effectiveness of our results.

  11. Asymptotic estimates and exponential stability for higher-order monotone difference equations

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    Pituk Mihály

    2005-01-01

    Full Text Available Asymptotic estimates are established for higher-order scalar difference equations and inequalities the right-hand sides of which generate a monotone system with respect to the discrete exponential ordering. It is shown that in some cases the exponential estimates can be replaced with a more precise limit relation. As corollaries, a generalization of discrete Halanay-type inequalities and explicit sufficient conditions for the global exponential stability of the zero solution are given.

  12. Asymptotic estimates and exponential stability for higher-order monotone difference equations

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    Mihály Pituk

    2005-03-01

    Full Text Available Asymptotic estimates are established for higher-order scalar difference equations and inequalities the right-hand sides of which generate a monotone system with respect to the discrete exponential ordering. It is shown that in some cases the exponential estimates can be replaced with a more precise limit relation. As corollaries, a generalization of discrete Halanay-type inequalities and explicit sufficient conditions for the global exponential stability of the zero solution are given.

  13. On the Linear Stability of the Fifth-Order WENO Discretization

    KAUST Repository

    Motamed, Mohammad

    2010-10-03

    We study the linear stability of the fifth-order Weighted Essentially Non-Oscillatory spatial discretization (WENO5) combined with explicit time stepping applied to the one-dimensional advection equation. We show that it is not necessary for the stability domain of the time integrator to include a part of the imaginary axis. In particular, we show that the combination of WENO5 with either the forward Euler method or a two-stage, second-order Runge-Kutta method is linearly stable provided very small time step-sizes are taken. We also consider fifth-order multistep time discretizations whose stability domains do not include the imaginary axis. These are found to be linearly stable with moderate time steps when combined with WENO5. In particular, the fifth-order extrapolated BDF scheme gave superior results in practice to high-order Runge-Kutta methods whose stability domain includes the imaginary axis. Numerical tests are presented which confirm the analysis. © Springer Science+Business Media, LLC 2010.

  14. Distributed-Order Dynamic Systems Stability, Simulation, Applications and Perspectives

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    Jiao, Zhuang; Podlubny, Igor

    2012-01-01

    Distributed-order differential equations, a generalization of fractional calculus, are of increasing importance in many fields of science and engineering from the behaviour of complex dielectric media to the modelling of nonlinear systems. This Brief will broaden the toolbox available to researchers interested in modeling, analysis, control and filtering. It contains contextual material outlining the progression from integer-order, through fractional-order to distributed-order systems. Stability issues are addressed with graphical and numerical results highlighting the fundamental differences between constant-, integer-, and distributed-order treatments. The power of the distributed-order model is demonstrated with work on the stability of noncommensurate-order linear time-invariant systems. Generic applications of the distributed-order operator follow: signal processing and viscoelastic damping of a mass–spring set up. A new general approach to discretization of distributed-order derivatives and integrals ...

  15. Strong Stability Preserving Explicit Runge--Kutta Methods of Maximal Effective Order

    KAUST Repository

    Hadjimichael, Yiannis

    2013-07-23

    We apply the concept of effective order to strong stability preserving (SSP) explicit Runge--Kutta methods. Relative to classical Runge--Kutta methods, methods with an effective order of accuracy are designed to satisfy a relaxed set of order conditions but yield higher order accuracy when composed with special starting and stopping methods. We show that this allows the construction of four-stage SSP methods with effective order four (such methods cannot have classical order four). However, we also prove that effective order five methods---like classical order five methods---require the use of nonpositive weights and so cannot be SSP. By numerical optimization, we construct explicit SSP Runge--Kutta methods up to effective order four and establish the optimality of many of them. Numerical experiments demonstrate the validity of these methods in practice.

  16. Strong Stability Preserving Explicit Runge--Kutta Methods of Maximal Effective Order

    KAUST Repository

    Hadjimichael, Yiannis; Macdonald, Colin B.; Ketcheson, David I.; Verner, James H.

    2013-01-01

    We apply the concept of effective order to strong stability preserving (SSP) explicit Runge--Kutta methods. Relative to classical Runge--Kutta methods, methods with an effective order of accuracy are designed to satisfy a relaxed set of order conditions but yield higher order accuracy when composed with special starting and stopping methods. We show that this allows the construction of four-stage SSP methods with effective order four (such methods cannot have classical order four). However, we also prove that effective order five methods---like classical order five methods---require the use of nonpositive weights and so cannot be SSP. By numerical optimization, we construct explicit SSP Runge--Kutta methods up to effective order four and establish the optimality of many of them. Numerical experiments demonstrate the validity of these methods in practice.

  17. Stability analysis of fractional-order Hopfield neural networks with time delays.

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    Wang, Hu; Yu, Yongguang; Wen, Guoguang

    2014-07-01

    This paper investigates the stability for fractional-order Hopfield neural networks with time delays. Firstly, the fractional-order Hopfield neural networks with hub structure and time delays are studied. Some sufficient conditions for stability of the systems are obtained. Next, two fractional-order Hopfield neural networks with different ring structures and time delays are developed. By studying the developed neural networks, the corresponding sufficient conditions for stability of the systems are also derived. It is shown that the stability conditions are independent of time delays. Finally, numerical simulations are given to illustrate the effectiveness of the theoretical results obtained in this paper. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Study of the stability of ordered phases in non-stoichiometric transition metal carbides and nitrides

    International Nuclear Information System (INIS)

    Landesman, J.P.

    1986-03-01

    After presenting the results of neutron diffraction experiments on the ordered compounds Nb 6 C 5 and Ti 2 N, we propose a classification of the ordered phases encountered in this class of compounds, and, using a tight-binding description of the electronic structure, we calculate the band energy for several ordered configurations and the disordered configuration, for a given metalloid vacancy concentration. We can then, on one hand, predict the relative stability (at O K) of the various ordered phases possible at this concentration - and these predictions are in good agreement with the experimental observations, mainly in the case of carbides - and on the other hand calculate the effective pair interactions V 1 and V 2 which appear in the Ising model and reconstruct theoretical stability maps, for any vacancy concentration, which are again in agreement with the phenomenological stability maps (overall agreement in the case of nitrides, more precise agreement in the case of carbides) [fr

  19. AMD-stability in the presence of first-order mean motion resonances

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    Petit, A. C.; Laskar, J.; Boué, G.

    2017-11-01

    The angular momentum deficit (AMD)-stability criterion allows to discriminate between a priori stable planetary systems and systems for which the stability is not granted and needs further investigations. AMD-stability is based on the conservation of the AMD in the averaged system at all orders of averaging. While the AMD criterion is rigorous, the conservation of the AMD is only granted in absence of mean-motion resonances (MMR). Here we extend the AMD-stability criterion to take into account mean-motion resonances, and more specifically the overlap of first-order MMR. If the MMR islands overlap, the system will experience generalized chaos leading to instability. The Hamiltonian of two massive planets on coplanar quasi-circular orbits can be reduced to an integrable one degree of freedom problem for period ratios close to a first-order MMR. We use the reduced Hamiltonian to derive a new overlap criterion for first-order MMR. This stability criterion unifies the previous criteria proposed in the literature and admits the criteria obtained for initially circular and eccentric orbits as limit cases. We then improve the definition of AMD-stability to take into account the short term chaos generated by MMR overlap. We analyze the outcome of this improved definition of AMD-stability on selected multi-planet systems from the Extrasolar Planets Encyclopædia.

  20. Time-Discrete Higher-Order ALE Formulations: Stability

    KAUST Repository

    Bonito, Andrea

    2013-01-01

    Arbitrary Lagrangian Eulerian (ALE) formulations deal with PDEs on deformable domains upon extending the domain velocity from the boundary into the bulk with the purpose of keeping mesh regularity. This arbitrary extension has no effect on the stability of the PDE but may influence that of a discrete scheme. We examine this critical issue for higher-order time stepping without space discretization. We propose time-discrete discontinuous Galerkin (dG) numerical schemes of any order for a time-dependent advection-diffusion-model problem in moving domains, and study their stability properties. The analysis hinges on the validity of the Reynold\\'s identity for dG. Exploiting the variational structure and assuming exact integration, we prove that our conservative and nonconservative dG schemes are equivalent and unconditionally stable. The same results remain true for piecewise polynomial ALE maps of any degree and suitable quadrature that guarantees the validity of the Reynold\\'s identity. This approach generalizes the so-called geometric conservation law to higher-order methods. We also prove that simpler Runge-Kutta-Radau methods of any order are conditionally stable, that is, subject to a mild ALE constraint on the time steps. Numerical experiments corroborate and complement our theoretical results. © 2013 Society for Industrial and Applied Mathematics.

  1. Comparison of the relative stability of pharmaceutical cocrystals consisting of paracetamol and dicarboxylic acids.

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    Suzuki, Naoto; Kawahata, Masatoshi; Yamaguchi, Kentaro; Suzuki, Toyofumi; Tomono, Kazuo; Fukami, Toshiro

    2018-04-01

    The aim of this study is to evaluate the relative stability of pharmaceutical cocrystals consisting of paracetamol (APAP) and oxalic acid (OXA) or maleic acid (MLA). These observations of cocrystal stability under various conditions are useful coformer criteria when cocrystals are selected as the active pharmaceutical ingredient in drug development. The relative stability was determined from the preferentially formed cocrystals under various conditions. Cocrystal of APAP-OXA was more stable than that of APAP-MLA in a ternary cogrinding system and possessed thermodynamical stability. On the other hand, when grinding with moisture or maintaining at high temperatures and relative humidity conditions, APAP-MLA was more stable, and OXA converted to OXA dihydrate. In the slurry method, APAP-OXA was more stable in aprotic solvents because the APAP-OXA with low-solubility product precipitated. The relative stability order was affected by preparing conditions of presence of moisture. This order might attribute to the small difference of crystal structure in the extension of the hydrogen bond network.

  2. Optimal explicit strong stability preserving Runge–Kutta methods with high linear order and optimal nonlinear order

    KAUST Repository

    Gottlieb, Sigal; Grant, Zachary; Higgs, Daniel

    2015-01-01

    High order spatial discretizations with monotonicity properties are often desirable for the solution of hyperbolic PDEs. These methods can advantageously be coupled with high order strong stability preserving time discretizations. The search

  3. Stability Analysis for Fractional-Order Linear Singular Delay Differential Systems

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    Hai Zhang

    2014-01-01

    Full Text Available We investigate the delay-independently asymptotic stability of fractional-order linear singular delay differential systems. Based on the algebraic approach, the sufficient conditions are presented to ensure the asymptotic stability for any delay parameter. By applying the stability criteria, one can avoid solving the roots of transcendental equations. An example is also provided to illustrate the effectiveness and applicability of the theoretical results.

  4. Dynamic Stability Analysis Using High-Order Interpolation

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    Juarez-Toledo C.

    2012-10-01

    Full Text Available A non-linear model with robust precision for transient stability analysis in multimachine power systems is proposed. The proposed formulation uses the interpolation of Lagrange and Newton's Divided Difference. The High-Order Interpolation technique developed can be used for evaluation of the critical conditions of the dynamic system.The technique is applied to a 5-area 45-machine model of the Mexican interconnected system. As a particular case, this paper shows the application of the High-Order procedure for identifying the slow-frequency mode for a critical contingency. Numerical examples illustrate the method and demonstrate the ability of the High-Order technique to isolate and extract temporal modal behavior.

  5. Fractional-Order Discrete-Time Laguerre Filters: A New Tool for Modeling and Stability Analysis of Fractional-Order LTI SISO Systems

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    Rafał Stanisławski

    2016-01-01

    Full Text Available This paper presents new results on modeling and analysis of dynamics of fractional-order discrete-time linear time-invariant single-input single-output (LTI SISO systems by means of new, two-layer, “fractional-order discrete-time Laguerre filters.” It is interesting that the fractionality of the filters at the upper system dynamics layer is directly projected from the lower Laguerre-based approximation layer for the Grünwald-Letnikov difference. A new stability criterion for discrete-time fractional-order Laguerre-based LTI SISO systems is introduced and supplemented with a stability preservation analysis. Both the stability criterion and the stability preservation analysis bring up rather surprising results, which is illustrated with simulation examples.

  6. Stabilization of third-order bilinear systems using constant controls

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    A. E. Golubev

    2014-01-01

    Full Text Available This paper deals with the zero equilibrium stabilization for dynamical systems that have control input singularities. A dynamical system with scalar control input is called nonregular if the coefficient of input becomes null on a subset of the phase space that contains the origin. One of the classes of nonregular dynamical systems is represented by bilinear systems. In case of second-order bilinear systems the necessary and sufficient conditions for the zero equilibrium stabilizability are known in the literature. However, in general case the stabilization problem in the presence of control input singularities has not been solved yet.In this note we solve the problem of the zero equilibrium stabilization for the third-order bilinear dynamical systems given in a canonical form. The solution is found in the class of constant controls. The necessary and sufficient conditions are obtained for the zero equilibrium stabilizability of the bilinear systems in question.The dependence of the zero equilibrium stabilizability on system parameter values is analyzed. The general criteria of stabilizability by means of constant controls are given for the bilinear systems in question. In case when all the system parameters have nonzero values the necessary and sufficient stabilizability conditions are proved. The case when some of the parameters are equal to zero is also considered.Further research can be focused on extending the obtained results to a higher-order case of bilinear and affine dynamical systems. The solution of the considered stabilization problem should also be found not only within constant controls but also in a class of state feedbacks, particularly, in the case when stabilizing constant control does not exist.One of the potential application areas for the obtained theoretical results is automatic control of technical plants like unmanned aerial vehicles and mobile robots.

  7. Ten year rank-order stability of personality traits and disorders in a clinical sample

    Science.gov (United States)

    Hopwood, Christopher J.; Morey, Leslie C.; Donnellan, M. Brent; Samuel, Douglas B.; Grilo, Carlos M.; McGlashan, Thomas H.; Shea, M. Tracie; Zanarini, Mary C.; Gunderson, John G.; Skodol, Andrew E.

    2012-01-01

    Objective To compare the 10-year retest stability of normal traits, pathological traits, and personality disorder dimensions in a clinical sample. Method Ten-year rank order stability estimates for the Revised NEO Personality Inventory, Schedule for Nonadaptive and Adaptive Personality, and Diagnostic Interview for DSM-IV Personality Disorders were evaluated before and after correcting for test-retest dependability and internal consistency in a clinical sample (N = 266). Results Dependability corrected stability estimates were generally in the range of .60–.90 for traits and .25–.65 for personality disorders. Conclusions The relatively lower stability of personality disorder symptoms may indicate important differences between pathological behaviors and relatively more stable self-attributed traits and imply that a full understanding of personality and personality pathology needs to take both traits and symptoms into account. The Five-Factor Theory distinction between basic tendencies and characteristic adaptations provides a theoretical framework for the separation of traits and disorders in terms of stability in which traits reflect basic tendencies that are stable and pervasive across situations, whereas personality disorder symptoms reflect characteristic maladaptations that are a function of both basic tendencies and environmental dynamics. PMID:22812532

  8. General Output Feedback Stabilization for Fractional Order Systems: An LMI Approach

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    Yiheng Wei

    2014-01-01

    Full Text Available This paper is concerned with the problem of general output feedback stabilization for fractional order linear time-invariant (FO-LTI systems with the fractional commensurate order 0<α<2. The objective is to design suitable output feedback controllers that guarantee the stability of the resulting closed-loop systems. Based on the slack variable method and our previous stability criteria, some new results in the form of linear matrix inequality (LMI are developed to the static and dynamic output feedback controllers synthesis for the FO-LTI system with 0<α<1. Furthermore, the results are extended to stabilize the FO-LTI systems with 1≤α<2. Finally, robust output feedback control is discussed. Numerical examples are given to illustrate the effectiveness of the proposed design methods.

  9. On the Linear Stability of the Fifth-Order WENO Discretization

    KAUST Repository

    Motamed, Mohammad; Macdonald, Colin B.; Ruuth, Steven J.

    2010-01-01

    , the fifth-order extrapolated BDF scheme gave superior results in practice to high-order Runge-Kutta methods whose stability domain includes the imaginary axis. Numerical tests are presented which confirm the analysis. © Springer Science+Business Media, LLC

  10. Weak Second Order Explicit Stabilized Methods for Stiff Stochastic Differential Equations

    KAUST Repository

    Abdulle, Assyr

    2013-01-01

    We introduce a new family of explicit integrators for stiff Itô stochastic differential equations (SDEs) of weak order two. These numerical methods belong to the class of one-step stabilized methods with extended stability domains and do not suffer from the step size reduction faced by standard explicit methods. The family is based on the standard second order orthogonal Runge-Kutta-Chebyshev (ROCK2) methods for deterministic problems. The convergence, meansquare, and asymptotic stability properties of the methods are analyzed. Numerical experiments, including applications to nonlinear SDEs and parabolic stochastic partial differential equations are presented and confirm the theoretical results. © 2013 Society for Industrial and Applied Mathematics.

  11. Lagrange α-exponential stability and α-exponential convergence for fractional-order complex-valued neural networks.

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    Jian, Jigui; Wan, Peng

    2017-07-01

    This paper deals with the problem on Lagrange α-exponential stability and α-exponential convergence for a class of fractional-order complex-valued neural networks. To this end, some new fractional-order differential inequalities are established, which improve and generalize previously known criteria. By using the new inequalities and coupling with the Lyapunov method, some effective criteria are derived to guarantee Lagrange α-exponential stability and α-exponential convergence of the addressed network. Moreover, the framework of the α-exponential convergence ball is also given, where the convergence rate is related to the parameters and the order of differential of the system. These results here, which the existence and uniqueness of the equilibrium points need not to be considered, generalize and improve the earlier publications and can be applied to monostable and multistable fractional-order complex-valued neural networks. Finally, one example with numerical simulations is given to show the effectiveness of the obtained results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Weak Second Order Explicit Stabilized Methods for Stiff Stochastic Differential Equations

    KAUST Repository

    Abdulle, Assyr; Vilmart, Gilles; Zygalakis, Konstantinos C.

    2013-01-01

    We introduce a new family of explicit integrators for stiff Itô stochastic differential equations (SDEs) of weak order two. These numerical methods belong to the class of one-step stabilized methods with extended stability domains and do not suffer

  13. Boundedness, Mittag-Leffler stability and asymptotical ω-periodicity of fractional-order fuzzy neural networks.

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    Wu, Ailong; Zeng, Zhigang

    2016-02-01

    We show that the ω-periodic fractional-order fuzzy neural networks cannot generate non-constant ω-periodic signals. In addition, several sufficient conditions are obtained to ascertain the boundedness and global Mittag-Leffler stability of fractional-order fuzzy neural networks. Furthermore, S-asymptotical ω-periodicity and global asymptotical ω-periodicity of fractional-order fuzzy neural networks is also characterized. The obtained criteria improve and extend the existing related results. To illustrate and compare the theoretical criteria, some numerical examples with simulation results are discussed in detail. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  14. Stability of the high-order finite elements for acoustic or elastic wave propagation with high-order time stepping

    KAUST Repository

    De Basabe, Jonás D.

    2010-04-01

    We investigate the stability of some high-order finite element methods, namely the spectral element method and the interior-penalty discontinuous Galerkin method (IP-DGM), for acoustic or elastic wave propagation that have become increasingly popular in the recent past. We consider the Lax-Wendroff method (LWM) for time stepping and show that it allows for a larger time step than the classical leap-frog finite difference method, with higher-order accuracy. In particular the fourth-order LWM allows for a time step 73 per cent larger than that of the leap-frog method; the computational cost is approximately double per time step, but the larger time step partially compensates for this additional cost. Necessary, but not sufficient, stability conditions are given for the mentioned methods for orders up to 10 in space and time. The stability conditions for IP-DGM are approximately 20 and 60 per cent more restrictive than those for SEM in the acoustic and elastic cases, respectively. © 2010 The Authors Journal compilation © 2010 RAS.

  15. A relation between Liapunov stability, non-wanderingness and Poisson stability

    International Nuclear Information System (INIS)

    Ahmad, K.H.

    1985-07-01

    In this work, some of the relations among Liapunov stability, non-wanderingness and Poisson stability are considered. In particular it is shown that for a non-wandering point in a set, positive (resp. negative) Liapunov stability in that set implies positive (resp. negative) Poisson stability in the same set. (author)

  16. Dependence of the relative stability between austenite and martensite phases on the atomic order in a Ni–Mn–In Metamagnetic Shape Memory Alloy

    International Nuclear Information System (INIS)

    Recarte, V.; Pérez-Landazábal, J.I.; Sánchez-Alarcos, V.

    2012-01-01

    Highlights: ► We analyze the influence of the atomic order on the transformations in Ni-Mn-In MSMA. ► Ordering decreases the martensitic transformation and increases the Curie temperature. ► The transformation entropy change depends on the atomic order. ► The shift of the transformation with the magnetic field depends on the atomic order. - Abstract: The influence of the atomic order on the magnetic properties and the relative stability between phases in a Ni–Mn–In Metamagnetic Shape Memory Alloy has been studied through the analysis of the effect of the different quenching treatments on the magnetic and structural transformation temperatures. As a consequence of the variation on the degree of long-range atomic order, the martensitic transformation temperature highly increases with the increasing quenching temperature whereas the Curie temperature slightly decreases. The modification of the atomic order brought by the quenching process also promotes a reduction of the entropy change linked to the martensitic transformation. In turn, no evolution of the magnetization change at the martensitic transformation is detected. According to the Claussius–Clapeyron equation, the achievable shift of the martensitic transformation temperature with the applied magnetic field also depends on the degree of atomic order.

  17. Global stability of stochastic high-order neural networks with discrete and distributed delays

    International Nuclear Information System (INIS)

    Wang Zidong; Fang Jianan; Liu Xiaohui

    2008-01-01

    High-order neural networks can be considered as an expansion of Hopfield neural networks, and have stronger approximation property, faster convergence rate, greater storage capacity, and higher fault tolerance than lower-order neural networks. In this paper, the global asymptotic stability analysis problem is considered for a class of stochastic high-order neural networks with discrete and distributed time-delays. Based on an Lyapunov-Krasovskii functional and the stochastic stability analysis theory, several sufficient conditions are derived, which guarantee the global asymptotic convergence of the equilibrium point in the mean square. It is shown that the stochastic high-order delayed neural networks under consideration are globally asymptotically stable in the mean square if two linear matrix inequalities (LMIs) are feasible, where the feasibility of LMIs can be readily checked by the Matlab LMI toolbox. It is also shown that the main results in this paper cover some recently published works. A numerical example is given to demonstrate the usefulness of the proposed global stability criteria

  18. Third-order least squares modelling of milling state term for improved computation of stability boundaries

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    C.G. Ozoegwu

    2016-01-01

    Full Text Available The general least squares model for milling process state term is presented. A discrete map for milling stability analysis that is based on the third-order case of the presented general least squares milling state term model is first studied and compared with its third-order counterpart that is based on the interpolation theory. Both numerical rate of convergence and chatter stability results of the two maps are compared using the single degree of freedom (1DOF milling model. The numerical rate of convergence of the presented third-order model is also studied using the two degree of freedom (2DOF milling process model. Comparison gave that stability results from the two maps agree closely but the presented map demonstrated reduction in number of needed calculations leading to about 30% savings in computational time (CT. It is seen in earlier works that accuracy of milling stability analysis using the full-discretization method rises from first-order theory to second-order theory and continues to rise to the third-order theory. The present work confirms this trend. In conclusion, the method presented in this work will enable fast and accurate computation of stability diagrams for use by machinists.

  19. Dynamic stability analysis of fractional order leaky integrator echo state neural networks

    Science.gov (United States)

    Pahnehkolaei, Seyed Mehdi Abedi; Alfi, Alireza; Tenreiro Machado, J. A.

    2017-06-01

    The Leaky integrator echo state neural network (Leaky-ESN) is an improved model of the recurrent neural network (RNN) and adopts an interconnected recurrent grid of processing neurons. This paper presents a new proof for the convergence of a Lyapunov candidate function to zero when time tends to infinity by means of the Caputo fractional derivative with order lying in the range (0, 1). The stability of Fractional-Order Leaky-ESN (FO Leaky-ESN) is then analyzed, and the existence, uniqueness and stability of the equilibrium point are provided. A numerical example demonstrates the feasibility of the proposed method.

  20. On global exponential stability of high-order neural networks with time-varying delays

    International Nuclear Information System (INIS)

    Zhang Baoyong; Xu Shengyuan; Li Yongmin; Chu Yuming

    2007-01-01

    This Letter investigates the problem of stability analysis for a class of high-order neural networks with time-varying delays. The delays are bounded but not necessarily differentiable. Based on the Lyapunov stability theory together with the linear matrix inequality (LMI) approach and the use of Halanay inequality, sufficient conditions guaranteeing the global exponential stability of the equilibrium point of the considered neural networks are presented. Two numerical examples are provided to demonstrate the effectiveness of the proposed stability criteria

  1. On global exponential stability of high-order neural networks with time-varying delays

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Baoyong [School of Automation, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu (China)]. E-mail: baoyongzhang@yahoo.com.cn; Xu Shengyuan [School of Automation, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu (China)]. E-mail: syxu02@yahoo.com.cn; Li Yongmin [School of Automation, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu (China) and Department of Mathematics, Huzhou Teacher' s College, Huzhou 313000, Zhejiang (China)]. E-mail: ymlwww@163.com; Chu Yuming [Department of Mathematics, Huzhou Teacher' s College, Huzhou 313000, Zhejiang (China)

    2007-06-18

    This Letter investigates the problem of stability analysis for a class of high-order neural networks with time-varying delays. The delays are bounded but not necessarily differentiable. Based on the Lyapunov stability theory together with the linear matrix inequality (LMI) approach and the use of Halanay inequality, sufficient conditions guaranteeing the global exponential stability of the equilibrium point of the considered neural networks are presented. Two numerical examples are provided to demonstrate the effectiveness of the proposed stability criteria.

  2. Thermal stability and molecular ordering of organic semiconductor monolayers: effect of an anchor group.

    Science.gov (United States)

    Jones, Andrew O F; Knauer, Philipp; Resel, Roland; Ringk, Andreas; Strohriegl, Peter; Werzer, Oliver; Sferrazza, Michele

    2015-06-08

    The thermal stability and molecular order in monolayers of two organic semiconductors, PBI-PA and PBI-alkyl, based on perylene derivatives with an identical molecular structure except for an anchor group for attachment to the substrate in PBI-PA, are reported. In situ X-ray reflectivity measurements are used to follow the stability of these monolayers in terms of order and thickness as temperature is increased. Films have thicknesses corresponding approximately to the length of one molecule; molecules stand upright on the substrate with a defined structure. PBI-PA monolayers have a high degree of order at room temperature and a stable film exists up to 250 °C, but decomposes rapidly above 300 °C. In contrast, stable physisorbed PBI-alkyl monolayers only exist up to 100 °C. Above the bulk melting point at 200 °C no more order exists. The results encourage using anchor groups in monolayers for various applications as it allows enhanced stability at the interface with the substrate. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Finite-time output feedback stabilization of high-order uncertain nonlinear systems

    Science.gov (United States)

    Jiang, Meng-Meng; Xie, Xue-Jun; Zhang, Kemei

    2018-06-01

    This paper studies the problem of finite-time output feedback stabilization for a class of high-order nonlinear systems with the unknown output function and control coefficients. Under the weaker assumption that output function is only continuous, by using homogeneous domination method together with adding a power integrator method, introducing a new analysis method, the maximal open sector Ω of output function is given. As long as output function belongs to any closed sector included in Ω, an output feedback controller can be developed to guarantee global finite-time stability of the closed-loop system.

  4. Mixed hyperbolic-second-order-parabolic formulations of general relativity

    International Nuclear Information System (INIS)

    Paschalidis, Vasileios

    2008-01-01

    Two new formulations of general relativity are introduced. The first one is a parabolization of the Arnowitt-Deser-Misner formulation and is derived by the addition of combinations of the constraints and their derivatives to the right-hand side of the Arnowitt-Deser-Misner evolution equations. The desirable property of this modification is that it turns the surface of constraints into a local attractor because the constraint propagation equations become second-order parabolic independently of the gauge conditions employed. This system may be classified as mixed hyperbolic--second-order parabolic. The second formulation is a parabolization of the Kidder-Scheel-Teukolsky formulation and is a manifestly mixed strongly hyperbolic--second-order-parabolic set of equations, bearing thus resemblance to the compressible Navier-Stokes equations. As a first test, a stability analysis of flat space is carried out and it is shown that the first modification exponentially damps and smoothes all constraint-violating modes. These systems provide a new basis for constructing schemes for long-term and stable numerical integration of the Einstein field equations.

  5. Stability analysis for neutral stochastic differential equation of second order driven by Poisson jumps

    Science.gov (United States)

    Chadha, Alka; Bora, Swaroop Nandan

    2017-11-01

    This paper studies the existence, uniqueness, and exponential stability in mean square for the mild solution of neutral second order stochastic partial differential equations with infinite delay and Poisson jumps. By utilizing the Banach fixed point theorem, first the existence and uniqueness of the mild solution of neutral second order stochastic differential equations is established. Then, the mean square exponential stability for the mild solution of the stochastic system with Poisson jumps is obtained with the help of an established integral inequality.

  6. Stability and Hopf Bifurcation of Fractional-Order Complex-Valued Single Neuron Model with Time Delay

    Science.gov (United States)

    Wang, Zhen; Wang, Xiaohong; Li, Yuxia; Huang, Xia

    2017-12-01

    In this paper, the problems of stability and Hopf bifurcation in a class of fractional-order complex-valued single neuron model with time delay are addressed. With the help of the stability theory of fractional-order differential equations and Laplace transforms, several new sufficient conditions, which ensure the stability of the system are derived. Taking the time delay as the bifurcation parameter, Hopf bifurcation is investigated and the critical value of the time delay for the occurrence of Hopf bifurcation is determined. Finally, two representative numerical examples are given to show the effectiveness of the theoretical results.

  7. Stability of a nonlinear second order equation under parametric bounded noise excitation

    International Nuclear Information System (INIS)

    Wiebe, Richard; Xie, Wei-Chau

    2016-01-01

    The motivation for the following work is a structural column under dynamic axial loads with both deterministic (harmonic transmitted forces from the surrounding structure) and random (wind and/or earthquake) loading components. The bounded noise used herein is a sinusoid with an argument composed of a random (Wiener) process deviation about a mean frequency. By this approach, a noise parameter may be used to investigate the behavior through the spectrum from simple harmonic forcing, to a bounded random process with very little harmonic content. The stability of both the trivial and non-trivial stationary solutions of an axially-loaded column (which is modeled as a second order nonlinear equation) under parametric bounded noise excitation is investigated by use of Lyapunov exponents. Specifically the effect of noise magnitude, amplitude of the forcing, and damping on stability of a column is investigated. First order averaging is employed to obtain analytical approximations of the Lyapunov exponents of the trivial solution. For the non-trivial stationary solution however, the Lyapunov exponents are obtained via Monte Carlo simulation as the stability equations become analytically intractable. (paper)

  8. Improving the stability of discretization zeros with the Taylor method using a generalization of the fractional-order hold

    Directory of Open Access Journals (Sweden)

    Zeng Cheng

    2014-12-01

    Full Text Available Remarkable improvements in the stability properties of discrete system zeros may be achieved by using a new design of the fractional-order hold (FROH circuit. This paper first analyzes asymptotic behaviors of the limiting zeros, as the sampling period T tends to zero, of the sampled-data models on the basis of the normal form representation for continuous-time systems with a new hold proposed. Further, we also give the approximate expression of limiting zeros of the resulting sampled-data system as power series with respect to a sampling period up to the third order term when the relative degree of the continuous-time system is equal to three, and the corresponding stability of the discretization zeros is discussed for fast sampling rates. Of particular interest are the stability conditions of sampling zeros in the case of a new FROH even though the relative degree of a continuous-time system is greater than two, whereas the conventional FROH fails to do so. An insightful interpretation of the obtained sampled-data model can be made in terms of minimal intersample ripple by design, where multirate sampled systems have a poor intersample behavior. Our results provide a more accurate approximation for asymptotic zeros, and certain known results on asymptotic behavior of limiting zeros are shown to be particular cases of the ideas presented here.

  9. Infant temperament: stability by age, gender, birth order, term status, and socioeconomic status.

    Science.gov (United States)

    Bornstein, Marc H; Putnick, Diane L; Gartstein, Maria A; Hahn, Chun-Shin; Auestad, Nancy; O'Connor, Deborah L

    2015-01-01

    Two complementary studies focused on stability of infant temperament across the 1st year and considered infant age, gender, birth order, term status, and socioeconomic status (SES) as moderators. Study 1 consisted of 73 mothers of firstborn term girls and boys queried at 2, 5, and 13 months of age. Study 2 consisted of 335 mothers of infants of different gender, birth order, term status, and SES queried at 6 and 12 months. Consistent positive and negative affectivity factors emerged at all time points across both studies. Infant temperament proved stable and robust across gender, birth order, term status, and SES. Stability coefficients for temperament factors and scales were medium to large for shorter ( 10 months) intervals. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  10. Effect of ordering of PtCu₃ nanoparticle structure on the activity and stability for the oxygen reduction reaction.

    Science.gov (United States)

    Hodnik, Nejc; Jeyabharathi, Chinnaiah; Meier, Josef C; Kostka, Alexander; Phani, Kanala L; Rečnik, Aleksander; Bele, Marjan; Hočevar, Stanko; Gaberšček, Miran; Mayrhofer, Karl J J

    2014-07-21

    In this study the performance enhancement effect of structural ordering for the oxygen reduction reaction (ORR) is systematically studied. Two samples of PtCu3 nanoparticles embedded on a graphitic carbon support are carefully prepared with identical initial composition, particle dispersion and size distribution, yet with different degrees of structural ordering. Thus we can eliminate all coinciding effects and unambiguously relate the improved activity of the ORR and more importantly the enhanced stability to the ordered nanostructure. Interestingly, the electrochemically induced morphological changes are common to both ordered and disordered samples. The observed effect could have a groundbreaking impact on the future directions in the rational design of active and stable platinum alloyed ORR catalysts.

  11. 75 FR 32846 - Final Rule Relating to Time and Order of Issuance of Domestic Relations Orders

    Science.gov (United States)

    2010-06-10

    ... is issued after the parties divorce. Example 3 illustrates that an order would not fail to be a QDRO... Alternate payee, Divorce, Domestic relations orders, Employee benefit plans, Marital property, Spouse, Plan administrator, Pensions, Qualified domestic relations orders. 0 For the reasons set forth in the preamble, the...

  12. On stability relative to vector elements of the orbit in general relativity motion

    International Nuclear Information System (INIS)

    Abdil'din, M.M.; Bejsenova, N.A.

    2002-01-01

    In this work a question of a new type of stability - stability relative to vector elements of the orbit is considered in general relativity mechanics in case of the Lenze-Thirring and two body rotation. (author)

  13. Stability and square integrability of solutions of nonlinear fourth order differential equations

    Directory of Open Access Journals (Sweden)

    Moussadek Remili

    2016-05-01

    Full Text Available The aim of the present paper is to establish a new result, which guarantees the asymptotic stability of zero solution and square integrability of solutions and their derivatives to nonlinear differential equations of fourth order.

  14. Higher-order scalar interactions and SM vacuum stability

    Energy Technology Data Exchange (ETDEWEB)

    Lalak, Zygmunt; Lewicki, Marek; Olszewski, Paweł [Institute of Theoretical Physics, Faculty of Physics, University of Warsawul. Hoża 69, Warsaw (Poland)

    2014-05-26

    Investigation of the structure of the Standard Model effective potential at very large field strengths opens a window towards new phenomena and can reveal properties of the UV completion of the SM. The map of the lifetimes of the vacua of the SM enhanced by nonrenormalizable scalar couplings has been compiled to show how new interactions modify stability of the electroweak vacuum. Whereas it is possible to stabilize the SM by adding Planck scale suppressed interactions and taking into account running of the new couplings, the generic effect is shortening the lifetime and hence further destabilisation of the SM electroweak vacuum. These findings have been illustrated with phase diagrams of modified SM-like models. It has been demonstrated that stabilisation can be achieved by lowering the suppression scale of higher order operators while picking up such combinations of new couplings, which do not deepen the new minima of the potential. Our results show the dependence of the lifetime of the electroweak minimum on the magnitude of the new couplings, including cases with very small couplings (which means very large effective suppression scale) and couplings vastly different in magnitude (which corresponds to two different suppression scales)

  15. Linear and nonlinear stability analysis in BWRs applying a reduced order model

    Energy Technology Data Exchange (ETDEWEB)

    Olvera G, O. A.; Espinosa P, G.; Prieto G, A., E-mail: omar_olverag@hotmail.com [Universidad Autonoma Metropolitana, Unidad Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, 09340 Ciudad de Mexico (Mexico)

    2016-09-15

    Boiling Water Reactor (BWR) stability studies are generally conducted through nonlinear reduced order models (Rom) employing various techniques such as bifurcation analysis and time domain numerical integration. One of those models used for these studies is the March-Leuba Rom. Such model represents qualitatively the dynamic behavior of a BWR through a one-point reactor kinetics, a one node representation of the heat transfer process in fuel, and a two node representation of the channel Thermal hydraulics to account for the void reactivity feedback. Here, we study the effect of this higher order model on the overall stability of the BWR. The change in the stability boundaries is determined by evaluating the eigenvalues of the Jacobian matrix. The nonlinear model is also integrated numerically to show that in the nonlinear region, the system evolves to stable limit cycles when operating close to the stability boundary. We also applied a new technique based on the Empirical Mode Decomposition (Emd) to estimate a parameter linked with stability in a BWR. This instability parameter is not exactly the classical Decay Ratio (Dr), but it will be linked with it. The proposed method allows decomposing the analyzed signal in different levels or mono-component functions known as intrinsic mode functions (Imf). One or more of these different modes can be associated to the instability problem in BWRs. By tracking the instantaneous frequencies (calculated through Hilbert Huang Transform (HHT) and the autocorrelation function (Acf) of the Imf linked to instability. The estimation of the proposed parameter can be achieved. The current methodology was validated with simulated signals of the studied model. (Author)

  16. Linear and nonlinear stability analysis in BWRs applying a reduced order model

    International Nuclear Information System (INIS)

    Olvera G, O. A.; Espinosa P, G.; Prieto G, A.

    2016-09-01

    Boiling Water Reactor (BWR) stability studies are generally conducted through nonlinear reduced order models (Rom) employing various techniques such as bifurcation analysis and time domain numerical integration. One of those models used for these studies is the March-Leuba Rom. Such model represents qualitatively the dynamic behavior of a BWR through a one-point reactor kinetics, a one node representation of the heat transfer process in fuel, and a two node representation of the channel Thermal hydraulics to account for the void reactivity feedback. Here, we study the effect of this higher order model on the overall stability of the BWR. The change in the stability boundaries is determined by evaluating the eigenvalues of the Jacobian matrix. The nonlinear model is also integrated numerically to show that in the nonlinear region, the system evolves to stable limit cycles when operating close to the stability boundary. We also applied a new technique based on the Empirical Mode Decomposition (Emd) to estimate a parameter linked with stability in a BWR. This instability parameter is not exactly the classical Decay Ratio (Dr), but it will be linked with it. The proposed method allows decomposing the analyzed signal in different levels or mono-component functions known as intrinsic mode functions (Imf). One or more of these different modes can be associated to the instability problem in BWRs. By tracking the instantaneous frequencies (calculated through Hilbert Huang Transform (HHT) and the autocorrelation function (Acf) of the Imf linked to instability. The estimation of the proposed parameter can be achieved. The current methodology was validated with simulated signals of the studied model. (Author)

  17. Transient Angle Stability Analysis of Grid-Connected Converters with the First-order Active Power Loop

    DEFF Research Database (Denmark)

    Wu, Heng; Wang, Xiongfei

    2018-01-01

    . To tackle this challenge, this paper employs the phase portrait to analyze the transient stability of power converters, and it is found that the better transient stability performance can be achieved if the grid-connected converters are controlled as the first-order nonlinear system. Simulations...

  18. Quota Swapping, Relative Stability, and Transparency

    NARCIS (Netherlands)

    Hoefnagel, E.W.J.; Vos, de B.I.; Buisman, F.C.

    2015-01-01

    One of the oldest elements of the Common Fisheries Policy (CFP) is the principle of ‘relative stability’. Relative stability means that yearly established Total Allowable Catches (TACs) for each fish stock are divided between the Member States of the European Union (EU) according to a fixed

  19. Full Stability of Locally Optimal Solutions in Second-Order Cone Programs

    Czech Academy of Sciences Publication Activity Database

    Mordukhovich, B. S.; Outrata, Jiří; Sarabi, E.

    2014-01-01

    Roč. 24, č. 4 (2014), s. 1581-1613 ISSN 1052-6234 R&D Projects: GA ČR GAP402/12/1309 Grant - others:Australian Research Council(AU) DP-12092508; Australian Research Council(AU) DP-110102011; Portuguese Foundation of Science and Technologies(PT) MAT/11109; USA National Science Foundation(US) DMS-1007132 Institutional support: RVO:67985556 Keywords : variational analysis * second-order cone programming * full stability of local minimizers * nondegeneracy * strong regularity * quadratic growth * second-order subdifferentials * coderivatives Subject RIV: BA - General Mathematics Impact factor: 1.829, year: 2014 http://library.utia.cas.cz/separaty/2014/MTR/outrata-0434303.pdf

  20. Feasibility of self-correcting quantum memory and thermal stability of topological order

    International Nuclear Information System (INIS)

    Yoshida, Beni

    2011-01-01

    Recently, it has become apparent that the thermal stability of topologically ordered systems at finite temperature, as discussed in condensed matter physics, can be studied by addressing the feasibility of self-correcting quantum memory, as discussed in quantum information science. Here, with this correspondence in mind, we propose a model of quantum codes that may cover a large class of physically realizable quantum memory. The model is supported by a certain class of gapped spin Hamiltonians, called stabilizer Hamiltonians, with translation symmetries and a small number of ground states that does not grow with the system size. We show that the model does not work as self-correcting quantum memory due to a certain topological constraint on geometric shapes of its logical operators. This quantum coding theoretical result implies that systems covered or approximated by the model cannot have thermally stable topological order, meaning that systems cannot be stable against both thermal fluctuations and local perturbations simultaneously in two and three spatial dimensions. - Highlights: → We define a class of physically realizable quantum codes. → We determine their coding and physical properties completely. → We establish the connection between topological order and self-correcting memory. → We find they do not work as self-correcting quantum memory. → We find they do not have thermally stable topological order.

  1. Stabilization of solutions to higher-order nonlinear Schrodinger equation with localized damping

    Directory of Open Access Journals (Sweden)

    Eleni Bisognin

    2007-01-01

    Full Text Available We study the stabilization of solutions to higher-order nonlinear Schrodinger equations in a bounded interval under the effect of a localized damping mechanism. We use multiplier techniques to obtain exponential decay in time of the solutions of the linear and nonlinear equations.

  2. THE STABILITY OF THE PERIODIC SOLUTIONS OF SECOND ORDER HAMILTONIAN SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper studies the stability of the periodic solutions of the second order Hamiltonian systems with even superquadratic or subquadratic potentials. The author proves that in the subquadratic case, there exist infinite geometrically distinct elliptic periodic solutions, and in the superquadratic case, there exist infinite geometrically distinct periodic solutions with at most one instability direction if they are half period non-degenerate, otherwise they are elliptic.

  3. Diffusive Phenomena and the Austenite/Martensite Relative Stability in Cu-Based Shape-Memory Alloys

    Science.gov (United States)

    Pelegrina, J. L.; Yawny, A.; Sade, M.

    2018-02-01

    The main characteristic of martensitic phase transitions is the coordinate movement of the atoms which takes place athermally, without the contribution of diffusion during its occurrence. However, the impacts of diffusive phenomena on the relative stability between the phases involved and, consequently, on the associated transformation temperatures and functional properties can be significant. This is particularly evident in the case of Cu-based shape-memory alloys where atomic diffusion in both austenite and martensite metastable phases might occur even at room-temperature levels, giving rise to a variety of intensively studied phenomena. In the present study, the progresses made in the understanding of three selected diffusion-related effects of importance in Cu-Zn-Al and Cu-Al-Be alloys are reviewed. They are the after-quench retained disorder in the austenitic structure and its subsequent reordering, the stabilization of the martensite, and the effect of applied stress on the austenitic order. It is shown how the experimental results obtained from tests performed on single crystal material can be rationalized under the shed of a model developed to evaluate the variation of the relative stability between the phases in terms of atom pairs interchanges.

  4. On the stability of projection methods for the incompressible Navier-Stokes equations based on high-order discontinuous Galerkin discretizations

    Science.gov (United States)

    Fehn, Niklas; Wall, Wolfgang A.; Kronbichler, Martin

    2017-12-01

    The present paper deals with the numerical solution of the incompressible Navier-Stokes equations using high-order discontinuous Galerkin (DG) methods for discretization in space. For DG methods applied to the dual splitting projection method, instabilities have recently been reported that occur for small time step sizes. Since the critical time step size depends on the viscosity and the spatial resolution, these instabilities limit the robustness of the Navier-Stokes solver in case of complex engineering applications characterized by coarse spatial resolutions and small viscosities. By means of numerical investigation we give evidence that these instabilities are related to the discontinuous Galerkin formulation of the velocity divergence term and the pressure gradient term that couple velocity and pressure. Integration by parts of these terms with a suitable definition of boundary conditions is required in order to obtain a stable and robust method. Since the intermediate velocity field does not fulfill the boundary conditions prescribed for the velocity, a consistent boundary condition is derived from the convective step of the dual splitting scheme to ensure high-order accuracy with respect to the temporal discretization. This new formulation is stable in the limit of small time steps for both equal-order and mixed-order polynomial approximations. Although the dual splitting scheme itself includes inf-sup stabilizing contributions, we demonstrate that spurious pressure oscillations appear for equal-order polynomials and small time steps highlighting the necessity to consider inf-sup stability explicitly.

  5. Hyers-Ulam stability for second-order linear differential equations with boundary conditions

    Directory of Open Access Journals (Sweden)

    Pasc Gavruta

    2011-06-01

    Full Text Available We prove the Hyers-Ulam stability of linear differential equations of second-order with boundary conditions or with initial conditions. That is, if y is an approximate solution of the differential equation $y''+ eta (x y = 0$ with $y(a = y(b =0$, then there exists an exact solution of the differential equation, near y.

  6. Stability of relative equilibria of three vortices

    DEFF Research Database (Denmark)

    Aref, Hassan

    2009-01-01

    Three point vortices on the unbounded plane have relative equilibria wherein the vortices either form an equilateral triangle or are collinear. While the stability analysis of the equilateral triangle configurations is straightforward, that of the collinear relative equilibria is considerably mor...

  7. Global Mittag-Leffler stability analysis of fractional-order impulsive neural networks with one-side Lipschitz condition.

    Science.gov (United States)

    Zhang, Xinxin; Niu, Peifeng; Ma, Yunpeng; Wei, Yanqiao; Li, Guoqiang

    2017-10-01

    This paper is concerned with the stability analysis issue of fractional-order impulsive neural networks. Under the one-side Lipschitz condition or the linear growth condition of activation function, the existence of solution is analyzed respectively. In addition, the existence, uniqueness and global Mittag-Leffler stability of equilibrium point of the fractional-order impulsive neural networks with one-side Lipschitz condition are investigated by the means of contraction mapping principle and Lyapunov direct method. Finally, an example with numerical simulation is given to illustrate the validity and feasibility of the proposed results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. ON THE BOUNDEDNESS AND THE STABILITY OF SOLUTION TO THIRD ORDER NON-LINEAR DIFFERENTIAL EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper we investigate the global asymptotic stability,boundedness as well as the ultimate boundedness of solutions to a general third order nonlinear differential equation,using complete Lyapunov function.

  9. Finite-Time Stability for Fractional-Order Bidirectional Associative Memory Neural Networks with Time Delays

    International Nuclear Information System (INIS)

    Xu Chang-Jin; Li Pei-Luan; Pang Yi-Cheng

    2017-01-01

    This paper is concerned with fractional-order bidirectional associative memory (BAM) neural networks with time delays. Applying Laplace transform, the generalized Gronwall inequality and estimates of Mittag–Leffler functions, some sufficient conditions which ensure the finite-time stability of fractional-order bidirectional associative memory neural networks with time delays are obtained. Two examples with their simulations are given to illustrate the theoretical findings. Our results are new and complement previously known results. (paper)

  10. Conflict of interests and social stability in the field of labour relations

    Directory of Open Access Journals (Sweden)

    Jovanović Predrag

    2013-01-01

    Full Text Available Labour relations are characterized by strong (existential conflict of interest between the employee and the employer. Therefore, labour relations must represent a legal term of the balance of interest of its entities, in order to be stable and have perspective. In other words, there is reciprocity of rights and obligations of the entities in labour relations. However, the employer is a stronger party, both legally and factually. The traditional task of labour law is to mitigate that legal and factual inequality of the employee and the employer to the extent necessary to ensure social security of employees and the employer himself, and social milieu and stability of the society as a whole. To this effect, appropriate limitations of the employer's authority are incorporated into the labour relations and appropriate principles for the operation of the system of labour relations are determined.

  11. Finite-time stability and synchronization of memristor-based fractional-order fuzzy cellular neural networks

    Science.gov (United States)

    Zheng, Mingwen; Li, Lixiang; Peng, Haipeng; Xiao, Jinghua; Yang, Yixian; Zhang, Yanping; Zhao, Hui

    2018-06-01

    This paper mainly studies the finite-time stability and synchronization problems of memristor-based fractional-order fuzzy cellular neural network (MFFCNN). Firstly, we discuss the existence and uniqueness of the Filippov solution of the MFFCNN according to the Banach fixed point theorem and give a sufficient condition for the existence and uniqueness of the solution. Secondly, a sufficient condition to ensure the finite-time stability of the MFFCNN is obtained based on the definition of finite-time stability of the MFFCNN and Gronwall-Bellman inequality. Thirdly, by designing a simple linear feedback controller, the finite-time synchronization criterion for drive-response MFFCNN systems is derived according to the definition of finite-time synchronization. These sufficient conditions are easy to verify. Finally, two examples are given to show the effectiveness of the proposed results.

  12. Stabilization and control of fractional order systems a sliding mode approach

    CERN Document Server

    Bandyopadhyay, Bijnan

    2015-01-01

    In the last two decades fractional differential equations have been used more frequently in physics, signal processing, fluid mechanics, viscoelasticity, mathematical biology, electro chemistry and many others. It opens a new and more realistic way to capture memory dependent phenomena and irregularities inside the systems by using more sophisticated mathematical analysis.This monograph is based on the authors' work on stabilization and control design for continuous and discrete fractional order systems. The initial two chapters and some parts of the third chapter are written in tutorial fashi

  13. Short-Range-Order Mineral Physical Protection On Black Carbon Stabilization

    Science.gov (United States)

    Liang, B.; Weng, Y. T.; Wang, C. C.; Song, Y. F.; Lehmann, J.; Wang, C. H.

    2015-12-01

    Soil organic matter is one of the largest reservoirs in global carbon cycle, and black carbon (BC) represents a chemical resistant component. Black C plays an important role in global climate change. Generally considered recalcitrant due to high aromaticity, the reactive surface and functional groups of BC are crucial for carbon sequestration in soils. Mineral sorption and physical protection is an important mechanism for BC long term stabilization and sequestration in environments. Previous studies on mineral protection of BC were limited to analysis techniques in two-dimensions, for example, by SEM, TEM, and NanoSIMS. Little is known about the scope of organo-mineral association, the in-situ distribution and forms of minerals, and the ultimate interplay of BC and minerals. The aim of this study is to investigate the three-dimensional interaction of organic C and minerals in submicron scale using synchrotron-based Transmission X-ray Microcopy (TXM) and Fourier-Transform Infrared Spectroscopy (FTIR). Abundant poorly-crystallined nano-minerals particles were observed. These short-range-order (SRO) minerals also aggregate into clusters and sheets, and form envelops-like structures on the surface of BC. On top of large surface contact area, the intimate interplay between BC and minerals reinforces the stability of both organic C and minerals, resulting from chemical bonding through cation bridging and ligand exchange. The mineral protection enhances BC stabilization and sequestration and lowers its bioavailability in environment. The results suggest that mineral physical protection for BC sequestration may be more important than previous understanding.

  14. Some new results on stability and synchronization for delayed inertial neural networks based on non-reduced order method.

    Science.gov (United States)

    Li, Xuanying; Li, Xiaotong; Hu, Cheng

    2017-12-01

    In this paper, without transforming the second order inertial neural networks into the first order differential systems by some variable substitutions, asymptotic stability and synchronization for a class of delayed inertial neural networks are investigated. Firstly, a new Lyapunov functional is constructed to directly propose the asymptotic stability of the inertial neural networks, and some new stability criteria are derived by means of Barbalat Lemma. Additionally, by designing a new feedback control strategy, the asymptotic synchronization of the addressed inertial networks is studied and some effective conditions are obtained. To reduce the control cost, an adaptive control scheme is designed to realize the asymptotic synchronization. It is noted that the dynamical behaviors of inertial neural networks are directly analyzed in this paper by constructing some new Lyapunov functionals, this is totally different from the traditional reduced-order variable substitution method. Finally, some numerical simulations are given to demonstrate the effectiveness of the derived theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Hyers-Ulam stability of linear second-order differential equations in complex Banach spaces

    Directory of Open Access Journals (Sweden)

    Yongjin Li

    2013-08-01

    Full Text Available We prove the Hyers-Ulam stability of linear second-order differential equations in complex Banach spaces. That is, if y is an approximate solution of the differential equation $y''+ alpha y'(t +eta y = 0$ or $y''+ alpha y'(t +eta y = f(t$, then there exists an exact solution of the differential equation near to y.

  16. Three year stability of Five-Factor Model personality traits in relation to changes in symptom levels in patients with schizophrenia or related disorders.

    Science.gov (United States)

    Boyette, Lindy-Lou; Nederlof, Jan; Meijer, Carin; de Boer, Froukje; de Haan, Lieuwe

    2015-09-30

    Five-Factor Model (FFM) personality traits are related to a wide range of clinical outcome in patients with psychotic disorders. However, it is not sufficiently clear whether psychotic illness, particularly fluctuation in negative symptoms and psychotic relapse, affects personality. The current study examined the 3-year temporal stability of FFM traits in 91 patients with non-affective psychotic disorders with a maximum duration of illness of 10 years and 32 control subjects without a (family member with) a diagnosis of psychotic illness. In patients, change in negative symptoms predicted changes in Neuroticism and (inversely) in Extraversion and Openness. However, when correcting for depressive symptoms, negative symptoms no longer predicted change in any FFM trait. Clinical characteristics, such as psychotic relapse, were also not found to be related to change in FFM traits. Patients showed a slight increase in Conscientiousness levels, the other FFM traits showed mean-level stability. Rank-order stability of the FFM traits was moderate to strong, although weaker for Neuroticism in patients. Our findings indicate that psychotic symptoms exert limited effect on the stability of FFM traits in patients with psychotic disorders. Consistent with general population findings, one should guard against state-trait confusion between Neuroticism/Extraversion and depression. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. Stability and ordering properties of fcc alloys based on Rh, Ir, Pd, and Pt

    Czech Academy of Sciences Publication Activity Database

    Turchi, P. E. A.; Drchal, Václav; Kudrnovský, Josef

    2006-01-01

    Roč. 74, č. 6 (2006), 064202/1-064202/12 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z1010914 Keywords : alloy phase stability * ordering in alloys * fcc alloys of Rh, Ir, Pd, Pt Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.107, year: 2006

  18. Microwave stability at transition

    International Nuclear Information System (INIS)

    Holt, J.A.; Colestock, P.L.

    1995-05-01

    The question of microwave stability at transition is revisited using a Vlasov approach retaining higher order terms in the particle dynamics near the transition energy. A dispersion relation is derived which can be solved numerically for the complex frequency in terms of the longitudinal impedance and other beam parameters. Stability near transition is examined and compared with simulation results

  19. Quark mass relations to four-loop order

    International Nuclear Information System (INIS)

    Marquard, Peter; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias

    2015-02-01

    We present results for the relation between a heavy quark mass defined in the on-shell and MS scheme to four-loop order. The method to compute the four-loop on-shell integral is briefly described and the new results are used to establish relations between various short-distance masses and the MS quark mass to next-to-next-to-next-to-leading order accuracy. These relations play an important role in the accurate determination of the MS heavy quark masses.

  20. Assessing the relative stabilities of engineered hemoglobins using electrospray mass spectrometry.

    Science.gov (United States)

    Apostol, I

    1999-07-15

    An ion trap mass spectrometer equipped with an electrospray source was used to examine the relative thermodynamic stabilities of various hemoglobins with respect to both tetramer dissociation and hemin dissociation. The results demonstrated that the stability of hemoglobin molecules can be differentiated by the amount of applied collision-induced dissociation (CID) energy necessary to break up the intact tetramer into its constituent globins. The stability of the intact tetramer was affected by single mutations in the beta-globins. The stabilities of the constituent hologlobins were assessed via trap CID of selected ions. The results demonstrated the importance of the contributions of the hologlobin components to the stability of the intact tetramer. Genetic fusion of two alpha-globins, through the introduction of a single glycine residue between the C-terminus of one alpha-chain and the N-terminus of the second, significantly increased the stability of the hemoglobin pseudo-tetramer. Chemical crosslinking of the beta-globins in addition to genetic fusion of alpha-globins further stabilized the hemoglobin molecule. A dihemoglobin molecule produced by the genetic fusion of two di-alpha-globins with a flexible linker demonstrated a decreased stability relative to the corresponding monohemoglobin. Copyright 1999 Academic Press.

  1. Optimal design and tuning of novel fractional order PID power system stabilizer using a new metaheuristic Bat algorithm

    Directory of Open Access Journals (Sweden)

    Lakhdar Chaib

    2017-06-01

    Full Text Available This paper proposes a novel robust power system stabilizer (PSS, based on hybridization of fractional order PID controller (PIλDμ and PSS for optimal stabilizer (FOPID-PSS for the first time, using a new metaheuristic optimization Bat algorithm (BA inspired by the echolocation behavior to improve power system stability. The problem of FOPID-PSS design is transformed as an optimization problem based on performance indices (PI, including Integral Absolute Error (IAE, Integral Squared Error (ISE, Integral of the Time-Weighted Absolute Error (ITAE and Integral of Time multiplied by the Squared Error (ITSE, where, BA is employed to obtain the optimal stabilizer parameters. In order to examine the robustness of FOPID-PSS, it has been tested on a Single Machine Infinite Bus (SMIB power system under different disturbances and operating conditions. The performance of the system with FOPID-PSS controller is compared with a PID-PSS and PSS. Further, the simulation results obtained with the proposed BA based FOPID-PSS are compared with those obtained with FireFly algorithm (FFA based FOPID-PSS. Simulation results show the effectiveness of BA for FOPID-PSS design, and superior robust performance for enhancement power system stability compared to other with different cases.

  2. Multi-Time Scale Model Order Reduction and Stability Consistency Certification of Inverter-Interfaced DG System in AC Microgrid

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Meng

    2018-01-01

    Full Text Available AC microgrid mainly comprise inverter-interfaced distributed generators (IIDGs, which are nonlinear complex systems with multiple time scales, including frequency control, time delay measurements, and electromagnetic transients. The droop control-based IIDG in an AC microgrid is selected as the research object in this study, which comprises power droop controller, voltage- and current-loop controllers, and filter and line. The multi-time scale characteristics of the detailed IIDG model are divided based on singular perturbation theory. In addition, the IIDG model order is reduced by neglecting the system fast dynamics. The static and transient stability consistency of the IIDG model order reduction are demonstrated by extracting features of the IIDG small signal model and using the quadratic approximation method of the stability region boundary, respectively. The dynamic response consistencies of the IIDG model order reduction are evaluated using the frequency, damping and amplitude features extracted by the Prony transformation. Results are applicable to provide a simplified model for the dynamic characteristic analysis of IIDG systems in AC microgrid. The accuracy of the proposed method is verified by using the eigenvalue comparison, the transient stability index comparison and the dynamic time-domain simulation.

  3. Stability and bifurcation of numerical discretization of a second-order delay differential equation with negative feedback

    International Nuclear Information System (INIS)

    Ding Xiaohua; Su Huan; Liu Mingzhu

    2008-01-01

    The paper analyzes a discrete second-order, nonlinear delay differential equation with negative feedback. The characteristic equation of linear stability is solved, as a function of two parameters describing the strength of the feedback and the damping in the autonomous system. The existence of local Hopf bifurcations is investigated, and the direction and stability of periodic solutions bifurcating from the Hopf bifurcation of the discrete model are determined by the Hopf bifurcation theory of discrete system. Finally, some numerical simulations are performed to illustrate the analytical results found

  4. Relative stability of radicals derived from artemisinin: A semiempirical and DFT study

    Science.gov (United States)

    Arantes, C.; de Araujo, M. T.; Taranto, A. G.; de M. Carneiro, J. W.

    The semiempirical AM1 and PM3 methods, as well as the density functional (DFT/B3LYP) approach using the 6-31g(d) basis set, were employed to calculate the relative stability of intermediate radicals derived from artemisinin, a sesquiterpene lactone having an endoperoxide bridge that is essential for its antimalarial activity. The compounds studied have their nonperoxidic oxygen atom of the trioxane ring and/or the carbonyl group replaced by a CH2 unit. Relative stabilities were calculated by means of isodesmic equations using artemisinin as reference. It was found that replacement of oxygen atoms decreases the relative stability of the anionic radical intermediates. In contrast, for compounds with inverted stereochemistry the intermediate radicals were found to be more stable than those with the artemisinin-like stereochemistry. These relative stabilities may modulate the antimalarial potency. Radicals centered on carbon are always more stable than the corresponding radicals centered on oxygen.

  5. Remarks on boiling water reactor stability analysis. Pt. 2. Stability monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Carsten; Hennig, Dieter; Hurtado, Antonio [Technische Univ. Dresden (Germany). Chair of Hydrogen and Nuclear Energy; Schuster, Roland [Kernkraftwerk Brunsbuettel GmbH und Co. oHG, Brunsbuettel (Germany); Lukas, Bernard [EnBW Kernkraft GmbH, Philippsburg (Germany). Kernkraftwerk Philippsburg; Aguirre, Carlos [Kernkraftwerk Leibstadt AG, Aargau (Switzerland)

    2012-12-15

    In part 1 of this article we explained the partly relative complex solution manifold of the differential equations describing the stability behaviour of a BWR, in particular the coexistence of different types of solutions, such as the coexistence of unstable limit cycles and stable fixed points are of interest from the operational safety point of view. The part 2 is devoted to the surveillance of the stability behaviour. We summarize some stability monitoring methods and suggest to support stability tests by RAM-ROM analyses in order to reveal in advance the stability 'landscape' of the BWR in a parameter region high sensitive for appearing of linear unstable states. The analysis of an especial stability test, performed at NPP Leibstadt (KKL), makes it clear that the measurement results can only be interpreted by application of bifurcation analysis. (orig.)

  6. Relative Stability of cis- and trans-Hydrindanones

    Directory of Open Access Journals (Sweden)

    Motoo Tori

    2015-01-01

    Full Text Available The relative stabilities of several cis- and trans-hydrindanones were compared using both isomerization experiments and MM2 calculations. The generally believed rule that cis-hydrindanones are more stable than trans-isomers is applicable, but is not always true. This review introduces examples, mainly from studies in our laboratory, to explain these facts.

  7. A stabilized second-order time accurate finite element formulation for incompressible viscous flow with heat transfer

    International Nuclear Information System (INIS)

    Curi, Marcos Filardy

    2011-01-01

    In view of the problem of global warming and the search for clean energy sources, a worldwide expansion on the use of nuclear energy is foreseen. Thus, the development of science and technology regarding nuclear power plants is essential, in particular in the field of reactor engineering. Fluid mechanics and heat transfer play an important role in the development of nuclear reactors. Computational Fluid Mechanics (CFD) is becoming ever more important in the optimization of cost and safety of the designs. This work presents a stabilized second-order time accurate finite element formulation for incompressible flows with heat transfer. A second order time discretization precedes a spatial discretization using finite elements. The terms that stabilize the finite element method arise naturally from the discretization process, rather than being introduced a priori in the variational formulation. The method was implemented in the program 'ns n ew s olvec2d av 2 M PI' written in FORTRAN90, developed in the Parallel Computing Laboratory at the Institute of Nuclear Engineering (LCP/IEN). Numerical solutions of some representative examples, including free, mixed and forced convection, demonstrate that the proposed stabilized formulation attains very good agreement with experimental and computational results available in the literature. (author)

  8. A stabilized MFE reduced-order extrapolation model based on POD for the 2D unsteady conduction-convection problem.

    Science.gov (United States)

    Xia, Hong; Luo, Zhendong

    2017-01-01

    In this study, we devote ourselves to establishing a stabilized mixed finite element (MFE) reduced-order extrapolation (SMFEROE) model holding seldom unknowns for the two-dimensional (2D) unsteady conduction-convection problem via the proper orthogonal decomposition (POD) technique, analyzing the existence and uniqueness and the stability as well as the convergence of the SMFEROE solutions and validating the correctness and dependability of the SMFEROE model by means of numerical simulations.

  9. Work-Family Conflict and Psychological Well-Being: Stability and Cross-Lagged Relations within One- and Six-Year Follow-Ups

    Science.gov (United States)

    Rantanen, Johanna; Kinnunen, Ulla; Feldt, Taru; Pulkkinen, Lea

    2008-01-01

    The rank-order stability and cross-lagged relations between work-to-family conflict (WFC), family-to-work conflict (FWC), and psychological well-being were examined in two longitudinal studies with full two-wave panel designs. In Study 1 (n = 365), the time lag was one year, and in Study 2 (n = 153), six years. The Structural Equation Modeling…

  10. Gauge stability of 3+1 formulations of general relativity

    International Nuclear Information System (INIS)

    Khokhlov, A M; Novikov, I D

    2002-01-01

    We present a general approach to the analysis of gauge stability of 3+1 formulations of general relativity (GR). Evolution of coordinate perturbations and the corresponding perturbations of lapse and shift can be described by a system of eight quasi-linear partial differential equations. Stability with respect to gauge perturbations depends on the choice of gauge and a background metric, but it does not depend on a particular form of a 3+1 system if its constrained solutions are equivalent to those of the Einstein equations. Stability of a number of known gauges is investigated in the limit of short-wavelength perturbations. All fixed gauges except a synchronous gauge are found to be ill posed. A maximal slicing gauge and its parabolic extension are shown to be ill posed as well. A necessary condition is derived for well-posedness of metric-dependent algebraic gauges. Well-posed metric-dependent gauges are found, however, to be generally unstable. Both instability and ill-posedness are associated with the existence of growing modes of coordinate perturbations related to perturbations of physical accelerations of reference frames

  11. Mechanical properties of ground state structures in substitutional ordered alloys: High strength, high ductility and high thermal stability

    International Nuclear Information System (INIS)

    Tawancy, H.M.; Aboelfotoh, M.O.

    2014-01-01

    We have studied the effect of atom arrangements in the ground state structures of substitutional ordered alloys on their mechanical properties using nickel–molybdenum-based alloys as model systems. Three alloys with nominal compositions of Ni–19.43 at% Mo, Ni–18.53 at% Mo–15.21 at% Cr and Ni–18.72 at% Mo–6.14 at% Nb are included in the study. In agreement with theoretical predictions, the closely related Pt 2 Mo-type, DO 22 and D1 a superlattices with similar energies are identified by electron diffraction of ground state structures, which can directly be derived from the parent disordered fcc structure by minor atom rearrangements on {420} fcc planes. The three superlattices are observed to coexist during the disorder–order transformation at 700 °C with the most stable superlattice being determined by the exact chemical composition. Although most of the slip systems in the parent disordered fcc structure are suppressed, many of the twinning systems remain operative in the superlattices favoring deformation by twinning, which leads to considerable strengthening while maintaining high ductility levels. Both the Pt 2 Mo-type and DO 22 superlattices are distinguished by high strength and high ductility due to their nanoscale microstructures, which have high thermal stability. However, the D1 a superlattice is found to exhibit poor thermal stability leading to considerable loss of ductility, which has been correlated with self-induced recrystallization by migration of grain boundaries

  12. Mechanical properties of ground state structures in substitutional ordered alloys: High strength, high ductility and high thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Tawancy, H.M., E-mail: tawancy@kfupm.edu.sa [Center for Engineering Research, Research Institute, King Fahd University of Petroleum and Minerals, KFUPM Box 1639, Dhahran 31261 (Saudi Arabia); Aboelfotoh, M.O., E-mail: oaboelfotoh@gmail.com [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27606 (United States)

    2014-05-01

    We have studied the effect of atom arrangements in the ground state structures of substitutional ordered alloys on their mechanical properties using nickel–molybdenum-based alloys as model systems. Three alloys with nominal compositions of Ni–19.43 at% Mo, Ni–18.53 at% Mo–15.21 at% Cr and Ni–18.72 at% Mo–6.14 at% Nb are included in the study. In agreement with theoretical predictions, the closely related Pt{sub 2}Mo-type, DO{sub 22} and D1{sub a} superlattices with similar energies are identified by electron diffraction of ground state structures, which can directly be derived from the parent disordered fcc structure by minor atom rearrangements on {420}{sub fcc} planes. The three superlattices are observed to coexist during the disorder–order transformation at 700 °C with the most stable superlattice being determined by the exact chemical composition. Although most of the slip systems in the parent disordered fcc structure are suppressed, many of the twinning systems remain operative in the superlattices favoring deformation by twinning, which leads to considerable strengthening while maintaining high ductility levels. Both the Pt{sub 2}Mo-type and DO{sub 22} superlattices are distinguished by high strength and high ductility due to their nanoscale microstructures, which have high thermal stability. However, the D1{sub a} superlattice is found to exhibit poor thermal stability leading to considerable loss of ductility, which has been correlated with self-induced recrystallization by migration of grain boundaries.

  13. Relation between birth order and interpersonal styles

    Directory of Open Access Journals (Sweden)

    Mauro de Oliveira Magalhães

    2009-10-01

    Full Text Available Interpersonal style is an aspect of personality related to the particular way individuals participate and gain influence in social contexts. It has its origin in childhood’s first social interactions within the family group. It is suggested that the individual position in the family structure, namely birth order, is an important variable in this process. The present study investigated combined effects of sex and birth order on interpersonal style. A sample of 435 college students (196 men and 239 women with ranging in age from 18 to 40 years (M = 23,3 answered the BASIS-A (Basic Adlerian Scales of Interpersonal Styles and a brief demographic questionnaire. Interactions between sex and birth order were found. Lastborn women showed greater tendency to search for success and social approval than firstborn women and lastborn men. Among men, lastborn revealed less need for social approval compared to firstborn and only children. First born men showed a higher need to attend social conventions and obtain success. The interaction between sex and birth order was relevant for the understanding of personality development in the context of family relations.   Keywords: birth order; interpersonal styles; personality.

  14. Lagrangian relative equilibria for a gyrostat in the three-body problem: bifurcations and stability

    Energy Technology Data Exchange (ETDEWEB)

    Guirao, Juan L G; Vera, Juan A, E-mail: juan.garcia@upct.e, E-mail: juanantonio.vera@upct.e [Departamento de Matematica Aplicada y EstadIstica, Universidad Politecnica de Cartagena, Hospital de Marina, 30203 Cartagena, Region de Murcia (Spain)

    2010-05-14

    In this paper we consider the non-canonical Hamiltonian dynamics of a gyrostat in the frame of the three-body problem. Using geometric/mechanic methods we study the approximate dynamics of the truncated Legendre series representation of the potential of an arbitrary order. Working in the reduced problem, we study the existence of relative equilibria that we refer to as Lagrange type following the analogy with the standard techniques. We provide necessary and sufficient conditions for the linear stability of Lagrangian relative equilibria if the gyrostat morphology form is close to a sphere. Thus, we generalize the classical results on equilibria of the three-body problem and many results on them obtained by the classic approach for the case of rigid bodies.

  15. Atomic ordering, phase stability and superconductivity in bulk and filamentary A15 type compounds

    International Nuclear Information System (INIS)

    Fluekiger, R.

    1987-05-01

    The influence of atomic ordering effects and ordering kinetics on the superconducting and metallurgical properties of A15 type compounds are critically discussed based on own and literature data. First, the techniques for determining the order parameter are reviewed. The dependence of T c vs. S in various A15 type compounds as a function of the quenching temperature and of the high energy particle irradiation fluence is discussed. A model for the disordering mechanism in A15 compounds is established, based on the new concept of the virtual lattice site. It is shown that the disordering mechanism is the same in both cases, high temperature heat treatment and high energy particle irradiation. The very complete representation of ordering effects also contains the variation of other properties, e.g. γ, θ D , ρ o and B c2 (0). Furthermore, it allows to draw empirical correlations between atomic ordering and A15 phase stability. Finally, it is shown on selected examples that the optimization of the critical current density at high fields in Nb 3 Sn wires by alloying is nothing else than a consequence of the occurrence of perfect atomic ordering in binary Nb 3 Sn. (orig.)

  16. A stabilized MFE reduced-order extrapolation model based on POD for the 2D unsteady conduction-convection problem

    Directory of Open Access Journals (Sweden)

    Hong Xia

    2017-05-01

    Full Text Available Abstract In this study, we devote ourselves to establishing a stabilized mixed finite element (MFE reduced-order extrapolation (SMFEROE model holding seldom unknowns for the two-dimensional (2D unsteady conduction-convection problem via the proper orthogonal decomposition (POD technique, analyzing the existence and uniqueness and the stability as well as the convergence of the SMFEROE solutions and validating the correctness and dependability of the SMFEROE model by means of numerical simulations.

  17. Stability and square integrability of derivatives of solutions of nonlinear fourth order differential equations with delay.

    Science.gov (United States)

    Korkmaz, Erdal

    2017-01-01

    In this paper, we give sufficient conditions for the boundedness, uniform asymptotic stability and square integrability of the solutions to a certain fourth order non-autonomous differential equations with delay by using Lyapunov's second method. The results obtained essentially improve, include and complement the results in the literature.

  18. Relation of vertical stability and aspect ratio in tokamaks

    International Nuclear Information System (INIS)

    Stambaugh, R.D.; Lao, L.L.; Lazarus, E.A.

    1992-01-01

    It is evaluated how the upper limit to plasma elongation κ, caused by vertical stability, varies with the aspect ratio A=R/a of the tokamak. Equilibria were generated with EFITD and the vertical stability was assessed by GATO. For a 'generic' tokamak with a superconducting wall conformal to the plasma shape and a distance 0.5 a away from the plasma edge and a constant current profile (q 0 =1.0, l i ≅1.0, q 95 =3.2) it is found that the maximum stable κ decreased only slowly from 2.65 at A=2.0 to 2.4 at A=6.0. To first order, a reasonable assumption in trade-off studies of new machine designs is no dependence of κ max on A. (author). Letter-to-the-editor. 13 refs, 3 figs, 1 tab

  19. Effect of Cation Ordering on the Performance and Chemical Stability of Layered Double Perovskite Cathodes

    Directory of Open Access Journals (Sweden)

    Carlos Bernuy-Lopez

    2018-01-01

    Full Text Available The effect of A-site cation ordering on the cathode performance and chemical stability of A-site cation ordered LaBaCo2O5+δ and disordered La0.5Ba0.5CoO3−δ materials are reported. Symmetric half-cells with a proton-conducting BaZr0.9Y0.1O3−δ electrolyte were prepared by ceramic processing, and good chemical compatibility of the materials was demonstrated. Both A-site ordered LaBaCo2O5+δ and A-site disordered La0.5Ba0.5CoO3−δ yield excellent cathode performance with Area Specific Resistances as low as 7.4 and 11.5 Ω·cm2 at 400 °C and 0.16 and 0.32 Ω·cm2 at 600 °C in 3% humidified synthetic air respectively. The oxygen vacancy concentration, electrical conductivity, basicity of cations and crystal structure were evaluated to rationalize the electrochemical performance of the two materials. The combination of high-basicity elements and high electrical conductivity as well as sufficient oxygen vacancy concentration explains the excellent performance of both LaBaCo2O5+δ and La0.5Ba0.5CoO3−δ materials at high temperatures. At lower temperatures, oxygen-deficiency in both materials is greatly reduced, leading to decreased performance despite the high basicity and electrical conductivity. A-site cation ordering leads to a higher oxygen vacancy concentration, which explains the better performance of LaBaCo2O5+δ. Finally, the more pronounced oxygen deficiency of the cation ordered polymorph and the lower chemical stability at reducing conditions were confirmed by coulometric titration.

  20. Application of a high-throughput relative chemical stability assay to screen therapeutic protein formulations by assessment of conformational stability and correlation to aggregation propensity.

    Science.gov (United States)

    Rizzo, Joseph M; Shi, Shuai; Li, Yunsong; Semple, Andrew; Esposito, Jessica J; Yu, Shenjiang; Richardson, Daisy; Antochshuk, Valentyn; Shameem, Mohammed

    2015-05-01

    In this study, an automated high-throughput relative chemical stability (RCS) assay was developed in which various therapeutic proteins were assessed to determine stability based on the resistance to denaturation post introduction to a chaotrope titration. Detection mechanisms of both intrinsic fluorescence and near UV circular dichroism (near-UV CD) are demonstrated. Assay robustness was investigated by comparing multiple independent assays and achieving r(2) values >0.95 for curve overlays. The complete reversibility of the assay was demonstrated by intrinsic fluorescence, near-UV CD, and biologic potency. To highlight the method utility, we compared the RCS assay with differential scanning calorimetry and dynamic scanning fluorimetry methodologies. Utilizing C1/2 values obtained from the RCS assay, formulation rank-ordering of 12 different mAb formulations was performed. The prediction of long-term stability on protein aggregation is obtained by demonstrating a good correlation with an r(2) of 0.83 between RCS and empirical aggregation propensity data. RCS promises to be an extremely useful tool to aid in candidate formulation development efforts based on the complete reversibility of the method to allow for multiple assessments without protein loss and the strong correlation between the C1/2 data obtained and accelerated stability under stressed conditions. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  1. Stability and square integrability of derivatives of solutions of nonlinear fourth order differential equations with delay

    Directory of Open Access Journals (Sweden)

    Erdal Korkmaz

    2017-06-01

    Full Text Available Abstract In this paper, we give sufficient conditions for the boundedness, uniform asymptotic stability and square integrability of the solutions to a certain fourth order non-autonomous differential equations with delay by using Lyapunov’s second method. The results obtained essentially improve, include and complement the results in the literature.

  2. Accuracy Enhanced Stability and Structure Preserving Model Reduction Technique for Dynamical Systems with Second Order Structure

    DEFF Research Database (Denmark)

    Tahavori, Maryamsadat; Shaker, Hamid Reza

    A method for model reduction of dynamical systems with the second order structure is proposed in this paper. The proposed technique preserves the second order structure of the system, and also preserves the stability of the original systems. The method uses the controllability and observability...... gramians within the time interval to build the appropriate Petrov-Galerkin projection for dynamical systems within the time interval of interest. The bound on approximation error is also derived. The numerical results are compared with the counterparts from other techniques. The results confirm...

  3. Hydrothermal stability investigation of micro- and mesoporous silica containing long-range ordered cobalt oxide clusters by XAS.

    Science.gov (United States)

    Liu, Liang; Wang, David K; Kappen, Peter; Martens, Dana L; Smart, Simon; Diniz da Costa, João C

    2015-07-15

    This work investigates the hydrothermal stability of cobalt doped silica materials with different Co/Si molar ratios (0, 0.05, 0.10, and 0.25). The resultant materials were characterized by N2 sorption and chemical structures by Raman and X-ray absorption spectroscopy before and after a harsh hydrothermal exposure (550 °C, 75 mol% vapour and 40 h). The cobalt silica materials showed a lower surface area loss from 48% to 12% with increasing Co/Si molar ratio from 0.05 to 0.25 and relatively maintaining their pore size distribution, while pure silica exhibited significant surface area reduction (80%) and pore size broadening. For low cobalt loading sample (Co/Si = 0.05), the cobalt was highly dispersed in the silica network in a tetrahedral coordination with oxygen and a small proportion of Co-Co interaction in the second shell. Long range order Co3O4 was observed when Co/Si molar ratio increased to 0.10 and 0.25. The hydrothermal exposure did not affect the local cobalt environments and no cobalt-silicon interaction was observed by X-ray absorption spectroscopy. The hydrothermal stability of the silica matrix was attributed to the physical barrier of cobalt oxide in opposing densification and silica mobility under harsh hydrothermal conditions.

  4. Boundary-bulk relation in topological orders

    Directory of Open Access Journals (Sweden)

    Liang Kong

    2017-09-01

    Full Text Available In this paper, we study the relation between an anomaly-free n+1D topological order, which are often called n+1D topological order in physics literature, and its nD gapped boundary phases. We argue that the n+1D bulk anomaly-free topological order for a given nD gapped boundary phase is unique. This uniqueness defines the notion of the “bulk” for a given gapped boundary phase. In this paper, we show that the n+1D “bulk” phase is given by the “center” of the nD boundary phase. In other words, the geometric notion of the “bulk” corresponds precisely to the algebraic notion of the “center”. We achieve this by first introducing the notion of a morphism between two (potentially anomalous topological orders of the same dimension, then proving that the notion of the “bulk” satisfies the same universal property as that of the “center” of an algebra in mathematics, i.e. “bulk = center”. The entire argument does not require us to know the precise mathematical description of a (potentially anomalous topological order. This result leads to concrete physical predictions.

  5. Crosslinked Enzyme Aggregates in Hierarchically-Ordered Mesoporous Silica: A Simple and Effective Method for Enzyme Stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Moon Il; Kim, Jungbae; Lee, Jinwoo; Jia, Hongfei; Na, Hyon Bin; Youn, Jongkyu; Kwak, Ja Hun; Dohnalkova, Alice; Grate, Jay W.; Wang, Ping; Hyeon, Taeghwan; Park, Hyun-Gyu; Chang, Ho Nam

    2007-02-01

    alpha-chymotrypsin (CT) and lipase (LP) were immobilized in hierarchically-ordered mesocellular mesoporous silica (HMMS) in a simple but effective way for the enzyme stabilization, which was achieved by the enzyme adsorption followed by glutaraldehyde (GA) crosslinking. This resulted in the formation of nanometer scale crosslinked enzyme aggregates (CLEAs) entrapped in the mesocellular pores of HMMS (37 nm), which did not leach out of HMMS through narrow mesoporous channels (13 nm). CLEA of alpha-chymotrypsin (CLEA-CT) in HMMS showed a high enzyme loading capacity and significantly increased enzyme stability. No activity decrease of CLEA-CT was observed for two weeks under even rigorously shaking condition, while adsorbed CT in HMMS and free CT showed a rapid inactivation due to the enzyme leaching and presumably autolysis, respectively. With the CLEA-CT in HMMS, however, there was no tryptic digestion observed suggesting that the CLEA-CT is not susceptible to autolysis. Moreover, CLEA of lipase (CLEA-LP) in HMMS retained 30% specific activity of free lipase with greatly enhanced stability. This work demonstrates that HMMS can be efficiently employed as host materials for enzyme immobilization leading to highly enhanced stability of the immobilized enzymes with high enzyme loading and activity.

  6. Existence and Globally Asymptotic Stability of Equilibrium Solution for Fractional-Order Hybrid BAM Neural Networks with Distributed Delays and Impulses

    Directory of Open Access Journals (Sweden)

    Hai Zhang

    2017-01-01

    Full Text Available This paper investigates the existence and globally asymptotic stability of equilibrium solution for Riemann-Liouville fractional-order hybrid BAM neural networks with distributed delays and impulses. The factors of such network systems including the distributed delays, impulsive effects, and two different fractional-order derivatives between the U-layer and V-layer are taken into account synchronously. Based on the contraction mapping principle, the sufficient conditions are derived to ensure the existence and uniqueness of the equilibrium solution for such network systems. By constructing a novel Lyapunov functional composed of fractional integral and definite integral terms, the globally asymptotic stability criteria of the equilibrium solution are obtained, which are dependent on the order of fractional derivative and network parameters. The advantage of our constructed method is that one may directly calculate integer-order derivative of the Lyapunov functional. A numerical example is also presented to show the validity and feasibility of the theoretical results.

  7. A condition for the overflow stability of second-order digital filters that is satisfied by all scaled state-space structures using saturation

    NARCIS (Netherlands)

    Ritzerfeld, J.H.F.

    1989-01-01

    A set of conditions is derived that ensures overflow stability of second-order digital filters for different classes of overflow arithmetics, involving only the elements of the state-transition matrix. The well-known arithmetic saturation, zeroing, and two's-complement lead to different stability

  8. High order quaternary arrangement confers increased structural stability to Brucella Spp. lumazine synthase

    Energy Technology Data Exchange (ETDEWEB)

    Zylberman, V.; Craig, P.O.; Klinke, S.; Cauerhff, A.; Goldbaum, F.A. [Instituto Leloir, Buenos Aires (Argentina); Braden, B.C. [Bowie State Univ., Maryland (United States)

    2004-07-01

    The penultimate step in the pathway of riboflavin biosynthesis is catalyzed by the enzyme lumazine synthase (LS). One of the most distinctive characteristics of this enzyme is the structural quaternary divergence found in different species. The protein exists as pentameric and icosahedral forms, built from practically the same structural monomeric unit. The pentameric structure is formed by five 18 kDa monomers, each extensively contacting neighboring monomers. The icosahedral structure consists of 60 LS monomers arranged as twelve pentamers giving rise to a capsid exhibiting icosahedral 532 symmetry. In all lumazine synthases studied, the topologically equivalent active sites are located at the interfaces between adjacent subunits in the pentameric modules. The Brucella spp. lumazine synthase (BLS) sequence clearly diverges from pentameric and icosahedral enzymes. This unusual divergence prompted to further investigate on its quaternary arrangement. In the present work, we demonstrate by means of solution Light Scattering and X-ray structural analyses that BLS assembles as a very stable dimer of pentamers representing a third category of quaternary assembly for lumazine synthases. We also describe by spectroscopic studies the thermodynamic stability of this oligomeric protein, and postulate a mechanism for dissociation/unfolding of this macromolecular assembly. The higher molecular order of BLS increases its stability 20 deg C compared to pentameric lumazine synthases. The decameric arrangement described in this work highlights the importance of quaternary interactions in the stabilization of proteins. (author)

  9. High order quaternary arrangement confers increased structural stability to Brucella Spp. lumazine synthase

    International Nuclear Information System (INIS)

    Zylberman, V.; Craig, P.O.; Klinke, S.; Cauerhff, A.; Goldbaum, F.A.; Braden, B.C.

    2004-01-01

    The penultimate step in the pathway of riboflavin biosynthesis is catalyzed by the enzyme lumazine synthase (LS). One of the most distinctive characteristics of this enzyme is the structural quaternary divergence found in different species. The protein exists as pentameric and icosahedral forms, built from practically the same structural monomeric unit. The pentameric structure is formed by five 18 kDa monomers, each extensively contacting neighboring monomers. The icosahedral structure consists of 60 LS monomers arranged as twelve pentamers giving rise to a capsid exhibiting icosahedral 532 symmetry. In all lumazine synthases studied, the topologically equivalent active sites are located at the interfaces between adjacent subunits in the pentameric modules. The Brucella spp. lumazine synthase (BLS) sequence clearly diverges from pentameric and icosahedral enzymes. This unusual divergence prompted to further investigate on its quaternary arrangement. In the present work, we demonstrate by means of solution Light Scattering and X-ray structural analyses that BLS assembles as a very stable dimer of pentamers representing a third category of quaternary assembly for lumazine synthases. We also describe by spectroscopic studies the thermodynamic stability of this oligomeric protein, and postulate a mechanism for dissociation/unfolding of this macromolecular assembly. The higher molecular order of BLS increases its stability 20 deg C compared to pentameric lumazine synthases. The decameric arrangement described in this work highlights the importance of quaternary interactions in the stabilization of proteins. (author)

  10. Advanced techniques for the analysis of crisis stability, deterrence, and latency

    Energy Technology Data Exchange (ETDEWEB)

    Canavan, G.H.

    1997-12-01

    Studies on crisis stability, deterrence, and latency are presented in chronological order, which also reflects their logical order of development, captures the main features of stability analysis; relates first strike, crisis, and arms control stability as seen from US and Russian perspective; and addresses questions such as whether uncertainty in damage preference or defense deployment can be destabilizing. It illustrates the problems with alternative metrics, latency and reconstitution, and deep unilateral and proportional force reductions.

  11. Conditional High-Order Boltzmann Machines for Supervised Relation Learning.

    Science.gov (United States)

    Huang, Yan; Wang, Wei; Wang, Liang; Tan, Tieniu

    2017-09-01

    Relation learning is a fundamental problem in many vision tasks. Recently, high-order Boltzmann machine and its variants have shown their great potentials in learning various types of data relation in a range of tasks. But most of these models are learned in an unsupervised way, i.e., without using relation class labels, which are not very discriminative for some challenging tasks, e.g., face verification. In this paper, with the goal to perform supervised relation learning, we introduce relation class labels into conventional high-order multiplicative interactions with pairwise input samples, and propose a conditional high-order Boltzmann Machine (CHBM), which can learn to classify the data relation in a binary classification way. To be able to deal with more complex data relation, we develop two improved variants of CHBM: 1) latent CHBM, which jointly performs relation feature learning and classification, by using a set of latent variables to block the pathway from pairwise input samples to output relation labels and 2) gated CHBM, which untangles factors of variation in data relation, by exploiting a set of latent variables to multiplicatively gate the classification of CHBM. To reduce the large number of model parameters generated by the multiplicative interactions, we approximately factorize high-order parameter tensors into multiple matrices. Then, we develop efficient supervised learning algorithms, by first pretraining the models using joint likelihood to provide good parameter initialization, and then finetuning them using conditional likelihood to enhance the discriminant ability. We apply the proposed models to a series of tasks including invariant recognition, face verification, and action similarity labeling. Experimental results demonstrate that by exploiting supervised relation labels, our models can greatly improve the performance.

  12. 3D elastic wave modeling using modified high‐order time stepping schemes with improved stability conditions

    KAUST Repository

    Chu, Chunlei; Stoffa, Paul L.; Seif, Roustam

    2009-01-01

    We present two Lax‐Wendroff type high‐order time stepping schemes and apply them to solving the 3D elastic wave equation. The proposed schemes have the same format as the Taylor series expansion based schemes, only with modified temporal extrapolation coefficients. We demonstrate by both theoretical analysis and numerical examples that the modified schemes significantly improve the stability conditions.

  13. Modelling the relative stability of carbon nanotubes exposed to environmental adsorbates and air

    International Nuclear Information System (INIS)

    Barnard, Amanda S

    2009-01-01

    In parallel with the development of technological applications for carbon nanotubes, issues related to toxicology and environmental impact are also under increased scrutiny. It is clear from the available literature that the integrity of future carbon nanotube-based devices, our ability to anticipate failure of these devices, and our ability to manage the toxicological and environmental impacts require a detailed understanding of the stability of pure and functionalized carbon nanotubes under a full range of environmental conditions. Motivated by this endeavour, the present study uses a general thermodynamic model to predict the relative stability of carbon nanotubes exposed to a variety of atmospheric adsorbates, and uses them to examine the stability of nanotubes in air, as a function of the relative humidity. In general the results indicate that the adsorption of a sparse coverage of air is thermodynamically favoured, depending on the humidity, and the stability of small diameter nanotubes may be improved by exposure to humid air.

  14. Stability of biogenic metal(loid) nanomaterials related to the colloidal stabilization theory of chemical nanostructures.

    Science.gov (United States)

    Piacenza, Elena; Presentato, Alessandro; Turner, Raymond J

    2018-02-25

    In the last 15 years, the exploitation of biological systems (i.e. plants, bacteria, mycelial fungi, yeasts, and algae) to produce metal(loid) (Me)-based nanomaterials has been evaluated as eco-friendly and a cost-effective alternative to the chemical synthesis processes. Although the biological mechanisms of biogenic Me-nanomaterial (Bio-Me-nanomaterials) production are not yet completely elucidated, a key advantage of such bio-nanostructures over those chemically synthesized is related to their natural thermodynamic stability, with several studies ascribed to the presence of an organic layer surrounding these Bio-Me-nanostructures. Different macromolecules (e.g. proteins, peptides, lipids, DNA, and polysaccharides) or secondary metabolites (e.g. flavonoids, terpenoids, glycosides, organic acids, and alkaloids) naturally produced by organisms have been indicated as main contributors to the stabilization of Bio-Me-nanostructures. Nevertheless, the chemical-physical mechanisms behind the ability of these molecules in providing stability to Bio-Me-nanomaterials are unknown. In this context, transposing the stabilization theory of chemically synthesized Me-nanomaterials (Ch-Me-nanomaterials) to biogenic materials can be used towards a better comprehension of macromolecules and secondary metabolites role as stabilizing agents of Bio-Me-nanomaterials. According to this theory, nanomaterials are generally featured by high thermodynamic instability in suspension, due to their high surface area and surface energy. This feature leads to the necessity to stabilize chemical nanostructures, even during or directly after their synthesis, through the development of (i) electrostatic, (ii) steric, or (iii) electrosteric interactions occurring between molecules and nanomaterials in suspension. Based on these three mechanisms, this review is focused on parallels between the stabilization of biogenic or chemical nanomaterials, suggesting which chemical-physical mechanisms may be

  15. Relation between birth order and interpersonal styles

    OpenAIRE

    Mauro de Oliveira Magalhães

    2009-01-01

    Interpersonal style is an aspect of personality related to the particular way individuals participate and gain influence in social contexts. It has its origin in childhood’s first social interactions within the family group. It is suggested that the individual position in the family structure, namely birth order, is an important variable in this process. The present study investigated combined effects of sex and birth order on interpersonal style. A sample of 435 college students (196 men and...

  16. Growth Properties of Wronskians in the Light of Relative Order

    Directory of Open Access Journals (Sweden)

    Sanjib Kumar Datta

    2014-02-01

    Full Text Available In this paper we study the comparative growth properties of composition of entire and meromorphic functions on the basis of relative order (relative lower order of Wronskians generated by entire and meromorphic functions.

  17. Laser beam pointing and stabilization by fractional-order PID control: Tuning rule and experiments

    KAUST Repository

    Al-Alwan, Asem Ibrahim Alwan; Guo, Xingang; Ndoye, Ibrahima; Laleg-Kirati, Taous-Meriem

    2017-01-01

    This paper studies the problem of high-precision positioning of laser beams by using a robust Fractional-Order Proportional-Integral-Derivative (FOPID) controller. The control problem addressed in laser beams aims to maintain the position of the laser beam on a Position Sensing Device (PSD) despite the effects of noise and active disturbances. The FOPID controller is well known for its simplicity with better tuning flexibility along with robustness to noise and output disturbance rejections. Thus, a control strategy based on FOPID to achieve the control objectives has been proposed. The FOPID gains and differentiation orders are optimally tuned in order to fulfill the robustness design specifications by solving a nonlinear optimization problem. A comparison to the conventional Proportional-Integral-Derivative (PID) and robust PID is also provided from simulation and experiment set-up. Due to sensor noise, practical PID controllers that filter the position signal before taking the derivative have been also proposed. Experimental results show that the requirements are totally met for the laser beam platform to be stabilized.

  18. Laser beam pointing and stabilization by fractional-order PID control: Tuning rule and experiments

    KAUST Repository

    Al-Alwan, Asem Ibrahim Alwan

    2017-10-24

    This paper studies the problem of high-precision positioning of laser beams by using a robust Fractional-Order Proportional-Integral-Derivative (FOPID) controller. The control problem addressed in laser beams aims to maintain the position of the laser beam on a Position Sensing Device (PSD) despite the effects of noise and active disturbances. The FOPID controller is well known for its simplicity with better tuning flexibility along with robustness to noise and output disturbance rejections. Thus, a control strategy based on FOPID to achieve the control objectives has been proposed. The FOPID gains and differentiation orders are optimally tuned in order to fulfill the robustness design specifications by solving a nonlinear optimization problem. A comparison to the conventional Proportional-Integral-Derivative (PID) and robust PID is also provided from simulation and experiment set-up. Due to sensor noise, practical PID controllers that filter the position signal before taking the derivative have been also proposed. Experimental results show that the requirements are totally met for the laser beam platform to be stabilized.

  19. Finite-Time Stability for Fractional-Order Bidirectional Associative Memory Neural Networks with Time Delays

    Science.gov (United States)

    Xu, Chang-Jin; Li, Pei-Luan; Pang, Yi-Cheng

    2017-02-01

    This paper is concerned with fractional-order bidirectional associative memory (BAM) neural networks with time delays. Applying Laplace transform, the generalized Gronwall inequality and estimates of Mittag-Leffler functions, some sufficient conditions which ensure the finite-time stability of fractional-order bidirectional associative memory neural networks with time delays are obtained. Two examples with their simulations are given to illustrate the theoretical findings. Our results are new and complement previously known results. Supported by National Natural Science Foundation of China under Grant Nos.~61673008, 11261010, 11101126, Project of High-Level Innovative Talents of Guizhou Province ([2016]5651), Natural Science and Technology Foundation of Guizhou Province (J[2015]2025 and J[2015]2026), 125 Special Major Science and Technology of Department of Education of Guizhou Province ([2012]011) and Natural Science Foundation of the Education Department of Guizhou Province (KY[2015]482)

  20. SECOND-ORDER VARIATIONAL ANALYSIS IN CONIC PROGRAMMING WITH APPLICATIONS TO OPTIMALITY AND STABILITY

    Czech Academy of Sciences Publication Activity Database

    Mordukhovich, B. S.; Outrata, Jiří; Ramírez, H. C.

    2015-01-01

    Roč. 25, č. 1 (2015), s. 76-101 ISSN 1052-6234 R&D Projects: GA ČR(CZ) GAP201/12/0671 Grant - others:Australian Research Council(AU) DP-110102011; USA National Science Foundation(US) DMS-1007132; Australian Reseach Council(AU) DP-12092508; Portuguese Foundation of Science and Technologies(PT) MAT/11109; FONDECYT Project(CL) 1110888; Universidad de Chile(CL) BASAL Project Centro de Modelamiento Matematico Institutional support: RVO:67985556 Keywords : variational analysis * second-order theory * conic programming * generalized differentiation * optimality conditions * isolated calmness * tilt stability Subject RIV: BA - General Mathematics Impact factor: 2.659, year: 2015 http://library.utia.cas.cz/separaty/2015/MTR/outrata-0439413.pdf

  1. Stability analysis of embedded solitons in the generalized third-order nonlinear Schroedinger equation

    International Nuclear Information System (INIS)

    Pelinovsky, Dmitry E.; Yang Jianke

    2005-01-01

    We study the generalized third-order nonlinear Schroedinger (NLS) equation which admits a one-parameter family of single-hump embedded solitons. Analyzing the spectrum of the linearization operator near the embedded soliton, we show that there exists a resonance pole in the left half-plane of the spectral parameter, which explains linear stability, rather than nonlinear semistability, of embedded solitons. Using exponentially weighted spaces, we approximate the resonance pole both analytically and numerically. We confirm in a near-integrable asymptotic limit that the resonance pole gives precisely the linear decay rate of parameters of the embedded soliton. Using conserved quantities, we qualitatively characterize the stable dynamics of embedded solitons

  2. Introduction: interregional relations in the world order

    Directory of Open Access Journals (Sweden)

    Jordi Bacaria

    2015-09-01

    Full Text Available This article will analyse factors which, since the end of last century, have made interregional relations very important to understand the world geopolitical and economic order. Interregional relations are defined as those which pertain to relations between regions or between a given state and a given region, or within a megaregion. This evolution results from: the growing demand in the emerging economies and the interaction among them, a new framework of interregional economic relations, and the development of new commercial channels. Finally, this paper will introduce the different articled included in this issue.

  3. Relational Stability in the Expression of Normality, Variation, and Control of Thyroid Function

    Science.gov (United States)

    Hoermann, Rudolf; Midgley, John E. M.; Larisch, Rolf; Dietrich, Johannes W.

    2016-01-01

    Thyroid hormone concentrations only become sufficient to maintain a euthyroid state through appropriate stimulation by pituitary thyroid-stimulating hormone (TSH). In such a dynamic system under constant high pressure, guarding against overstimulation becomes vital. Therefore, several defensive mechanisms protect against accidental overstimulation, such as plasma protein binding, conversion of T4 into the more active T3, active transmembrane transport, counter-regulatory activities of reverse T3 and thyronamines, and negative hypothalamic–pituitary–thyroid feedback control of TSH. TSH has gained a dominant but misguided role in interpreting thyroid function testing in assuming that its exceptional sensitivity thereby translates into superior diagnostic performance. However, TSH-dependent thyroid disease classification is heavily influenced by statistical analytic techniques such as uni- or multivariate-defined normality. This demands a separation of its conjoint roles as a sensitive screening test and accurate diagnostic tool. Homeostatic equilibria (set points) in healthy subjects are less variable and do not follow a pattern of random variation, rather indicating signs of early and progressive homeostatic control across the euthyroid range. In the event of imminent thyroid failure with a reduced FT4 output per unit TSH, conversion efficiency increases in order to maintain FT3 stability. In such situations, T3 stability takes priority over set point maintenance. This suggests a concept of relational stability. These findings have important implications for both TSH reference limits and treatment targets for patients on levothyroxine. The use of archival markers is proposed to facilitate the homeostatic interpretation of all parameters. PMID:27872610

  4. Charge orders in organic charge-transfer salts

    International Nuclear Information System (INIS)

    Kaneko, Ryui; Valentí, Roser; Tocchio, Luca F; Becca, Federico

    2017-01-01

    Motivated by recent experimental suggestions of charge-order-driven ferroelectricity in organic charge-transfer salts, such as κ -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl, we investigate magnetic and charge-ordered phases that emerge in an extended two-orbital Hubbard model on the anisotropic triangular lattice at 3/4 filling. This model takes into account the presence of two organic BEDT-TTF molecules, which form a dimer on each site of the lattice, and includes short-range intramolecular and intermolecular interactions and hoppings. By using variational wave functions and quantum Monte Carlo techniques, we find two polar states with charge disproportionation inside the dimer, hinting to ferroelectricity. These charge-ordered insulating phases are stabilized in the strongly correlated limit and their actual charge pattern is determined by the relative strength of intradimer to interdimer couplings. Our results suggest that ferroelectricity is not driven by magnetism, since these polar phases can be stabilized also without antiferromagnetic order and provide a possible microscopic explanation of the experimental observations. In addition, a conventional dimer-Mott state (with uniform density and antiferromagnetic order) and a nonpolar charge-ordered state (with charge-rich and charge-poor dimers forming a checkerboard pattern) can be stabilized in the strong-coupling regime. Finally, when electron–electron interactions are weak, metallic states appear, with either uniform charge distribution or a peculiar 12-site periodicity that generates honeycomb-like charge order. (paper)

  5. Formulation and stability testing of photolabile drugs.

    Science.gov (United States)

    Tønnesen, H H

    2001-08-28

    Exposure of a drug to irradiation can influence the stability of the formulation, leading to changes in the physicochemical properties of the product. The influence of excipients of frequently used stabilizers is often difficult to predict and, therefore, stability testing of the final preparation is important. The selection of a protective packaging must be based on knowledge about the wavelength causing the instability. Details on drug photoreactivity will also be helpful in order to minimize side-effects and/or optimize drug targeting by developing photoresponsive drug delivery systems. This review focuses on practical problems related to formulation and stability testing of photolabile drugs.

  6. Pointwise second-order necessary optimality conditions and second-order sensitivity relations in optimal control

    Science.gov (United States)

    Frankowska, Hélène; Hoehener, Daniel

    2017-06-01

    This paper is devoted to pointwise second-order necessary optimality conditions for the Mayer problem arising in optimal control theory. We first show that with every optimal trajectory it is possible to associate a solution p (ṡ) of the adjoint system (as in the Pontryagin maximum principle) and a matrix solution W (ṡ) of an adjoint matrix differential equation that satisfy a second-order transversality condition and a second-order maximality condition. These conditions seem to be a natural second-order extension of the maximum principle. We then prove a Jacobson like necessary optimality condition for general control systems and measurable optimal controls that may be only ;partially singular; and may take values on the boundary of control constraints. Finally we investigate the second-order sensitivity relations along optimal trajectories involving both p (ṡ) and W (ṡ).

  7. 78 FR 43856 - Harold Hanson; Order Relating to Harold Hanson

    Science.gov (United States)

    2013-07-22

    ... DEPARTMENT OF COMMERCE Bureau of Industry and Security Harold Hanson; Order Relating to Harold... Order Relating to Harold Hanson The Bureau of Industry and Security, U.S. Department of Commerce (``BIS... litigation or other civil proceedings in which the U.S. Department of Commerce is not a party. Fifth, that...

  8. Lime Stabilization of Fine-Grained Greenlandic Sediments in Relation to Construction Projects

    DEFF Research Database (Denmark)

    Jørgensen, Anders Stuhr; Ingeman-Nielsen, Thomas; Nielsen, Hans Rasmus

    2010-01-01

    to the cold climate, and it is therefore of great interest to study possible methods to improve the stability of the fine-grained sediments. This presentation will include results of laboratory studies of lime stabilization on a clay soil from Kangerlussuaq, western Greenland. The result includes tests...... of the optimum lime mixture in relation to both reaction time and temperature influence....

  9. A development of an evaluation flow chart for seismic stability of rock slopes based on relations between safety factor and sliding failure

    International Nuclear Information System (INIS)

    Kawai, Tadashi; Ishimaru, Makoto

    2010-01-01

    Recently, it is necessary to assess quantitatively seismic safety of critical facilities against the earthquake- induced rock slope failure from the viewpoint of seismic PSA. Under these circumstances, it is needed to evaluate the seismic stability of surrounding slopes against extremely strong ground motions. In order to evaluate the seismic stability of surrounding slopes, the most conventional method is to compare safety factors on an expected sliding surface, which is calculated from the stability analysis based on the limit equilibrium concept, to a critical value which judges stability or instability. The method is very effective to examine whether or not the sliding surface is safe. However, it does not mean that the sliding surface falls whenever the safety factor becomes smaller than the critical value during an earthquake. Therefore the authors develop a new evaluation flow chart for the seismic stability of rock slopes based on relations between safety factor and sliding failure. Furthermore, the developed flow chart was validated by comparing two kinds of safety factors calculated from a centrifuge test result concerned with a rock slope. (author)

  10. High-order non-uniform grid schemes for numerical simulation of hypersonic boundary-layer stability and transition

    International Nuclear Information System (INIS)

    Zhong Xiaolin; Tatineni, Mahidhar

    2003-01-01

    The direct numerical simulation of receptivity, instability and transition of hypersonic boundary layers requires high-order accurate schemes because lower-order schemes do not have an adequate accuracy level to compute the large range of time and length scales in such flow fields. The main limiting factor in the application of high-order schemes to practical boundary-layer flow problems is the numerical instability of high-order boundary closure schemes on the wall. This paper presents a family of high-order non-uniform grid finite difference schemes with stable boundary closures for the direct numerical simulation of hypersonic boundary-layer transition. By using an appropriate grid stretching, and clustering grid points near the boundary, high-order schemes with stable boundary closures can be obtained. The order of the schemes ranges from first-order at the lowest, to the global spectral collocation method at the highest. The accuracy and stability of the new high-order numerical schemes is tested by numerical simulations of the linear wave equation and two-dimensional incompressible flat plate boundary layer flows. The high-order non-uniform-grid schemes (up to the 11th-order) are subsequently applied for the simulation of the receptivity of a hypersonic boundary layer to free stream disturbances over a blunt leading edge. The steady and unsteady results show that the new high-order schemes are stable and are able to produce high accuracy for computations of the nonlinear two-dimensional Navier-Stokes equations for the wall bounded supersonic flow

  11. First-principles study of the nucleation and stability of ordered precipitates in ternary Al-Sc-Li alloys

    International Nuclear Information System (INIS)

    Mao, Z.; Chen, W.; Seidman, D.N.; Wolverton, C.

    2011-01-01

    First-principles density functional calculations are used to study the nucleation and stability of L1 2 -ordered precipitates in Al-Sc-Li alloys. For dilute Al alloys, there are three possible ordered L1 2 precipitates: Al 3 Sc, Al 3 Li and an Al 3 Sc/Al 3 Li core/shell structure. To calculate the nucleation behavior, information about bulk thermodynamics (both static total energies and vibrational free energies), interfacial energetics and coherency strain is required. The study finds the following: (1) the coherency strain energies for forming coherent interfaces between Al/Al 3 Sc, Al/Al 3 Li and Al 3 Sc/Al 3 Li are relatively small, owing to the small atomic size mismatches in these systems; (2) the sublattice site preferences of Sc and Li are calculated, and it is demonstrated that Sc and Li share the same sublattice sites in both Al 3 Sc(L1 2 ) and Al 3 Li(L1 2 ), in agreement with recent experimental results; (3) the calculated solubilities of Sc and Li in α-Al alloys are in good agreement with experimental values and, for Sc, agree well with prior first-principles results; (4) the interfacial energies for Al/Al 3 Sc, Al/Al 3 Li and Al 3 Sc/Al 3 Li for (1 0 0), (1 1 0) and (1 1 1) interfaces are calculated: the values of the Al/Al 3 Sc interfacial energies are significantly larger than those of the Al/Al 3 Li and Al 3 Sc/Al 3 Li interfaces; (5) combining the bulk and interfacial energies yields the nucleation barriers and critical radii for Al 3 Sc and Al 3 Li precipitates; and (6) the energetic stability of the Al 3 Sc/Al 3 Li core/shell structure is compared with individual Al 3 Sc and Al 3 Li nuclei, and the range of precipitate sizes for which the core/shell structure is energetically favored is determined quantitatively.

  12. Birth order and selected work-related personality variables.

    Science.gov (United States)

    Phillips, A S; Bedeian, A G; Mossholder, K W; Touliatos, J

    1988-12-01

    A possible link between birth order and various individual characteristics (e. g., intelligence, potential eminence, need for achievement, sociability) has been suggested by personality theorists such as Adler for over a century. The present study examines whether birth order is associated with selected personality variables that may be related to various work outcomes. 3 of 7 hypotheses were supported and the effect sizes for these were small. Firstborns scored significantly higher than later borns on measures of dominance, good impression, and achievement via conformity. No differences between firstborns and later borns were found in managerial potential, work orientation, achievement via independence, and sociability. The study's sample consisted of 835 public, government, and industrial accountants responding to a national US survey of accounting professionals. The nature of the sample may have been partially responsible for the results obtained. Its homogeneity may have caused any birth order effects to wash out. It can be argued that successful membership in the accountancy profession requires internalization of a set of prescribed rules and standards. It may be that accountants as a group are locked in to a behavioral framework. Any differentiation would result from spurious interpersonal differences, not from predictable birth-order related characteristics. A final interpretation is that birth order effects are nonexistent or statistical artifacts. Given the present data and particularistic sample, however, the authors have insufficient information from which to draw such a conclusion.

  13. Mediator of moderators: temporal stability of intention and the intention-behavior relation.

    Science.gov (United States)

    Sheeran, Paschal; Abraham, Charles

    2003-02-01

    Intention certainty, past behavior, self-schema, anticipated regret, and attitudinal versus normative control all have been found to moderate intention-behavior relations. It is argued that moderation occurs because these variables produce "strong" intentions. Stability of intention over time is a key index of intention strength. Consequently, it was hypothesized that temporal stability of intention would mediate moderation by these other moderators. Participants (N = 185) completed questionnaire measures of theory of planned behavior constructs and moderator variables at two time points and subsequently reported their exercise behavior. Findings showed that all of the moderators, including temporal stability, were associated with significant improvements in consistency between intention and behavior. Temporal stability also mediated the effects of the other moderators, supporting the study hypothesis. Copyright 2003 Society for Personality and Social Psychology, Inc.

  14. Brownian dynamics simulations of an order-disorder transition in sheared sterically stabilized colloidal suspensions

    International Nuclear Information System (INIS)

    Rigos, A.A.; Wilemski, G.

    1992-01-01

    The shear thinning behavior of a sterically stabilized nonaqueous colloidal suspension was investigated using nonequilibrium Brownian dynamics simulations of systems with 108 and 256 particles. At a volume fraction of 0.4, the suspension is thixotropic: it has a reversible shear thinning transition from a disordered state to an ordered, lamellar state with triangularly packed strings of particles. The time scale for the transition is set by the free particle diffusion constant. For the smaller system, the transition occurs gradually with increasing shear rate. For the larger system, the transition is sharp and discontinuous shear thinning is found. 34 refs., 9 figs., 1 tab

  15. Body posture and postural stability of people practicing qigong

    Directory of Open Access Journals (Sweden)

    Jacek Wilczyński

    2015-07-01

    Full Text Available Introduction: Correct and stable posture is essential for the implementation of the majority of voluntary movements and locomotion. The study of postural stability is an element of clinical trials evaluating physical activity in order to determine the optimal therapeutic procedures. Qigong exercises are not only a form of prevention, helpful in maintaining wellbeing, but also a means of therapy in many diseases, including disorders of postural stability. Aim of the research: To analyse the association between the quality of posture and postural stability of people practicing qigong. Material and methods : The study involved 32 people. The mean age of those tested was 54 years. Posture study used optoelectronic method Diers formetric III 4D. Postural stability was tested on the platform Biodex Balance System. The studies were performed at the Posture Laboratory of the Institute of Physiotherapy at Jan Kochanowski University in Kielce. Results and conclusions : Spearman rank order correlation showed a positive correlation of relative rotation of the spine area with a general indicator of stability (p = 0.0206 at an average level (R = 0.4075 and with the index of the stability A/P (p = 0.0310, although at a lower level (R = 0.3819. With the increase in the relative rotation of the spine area the overall stability indicator and stability indicator A/P also increased. Significant positive correlations were also seen for the surface rotation (+max and a general indication of the stability and the stability index A/P. With the increase of surface rotation (+max of the spine the overall stability indicator and stability indicator A/P also increased.

  16. Salt marsh stability modelled in relation to sea level rise

    DEFF Research Database (Denmark)

    Bartholdy, Jesper; Bartholdy, Anders; Kroon, Aart

    2010-01-01

    thickness. Autocompaction was incorporated in the model, and shown to play a major role for the translation of accretion rates measured as length per unit time to accumulation rates measured as mass per area per unit time. This is important, even for shallow salt marsh deposits for which it is demonstrated...... that mass depth down core can be directly related to the bulk dry density of the surface layer by means of a logarithmic function. The results allow for an evaluation of the use of marker horizons in the topmost layers and show that it is important to know the level of the marker in relation to the salt...... marsh base. In general, deeper located markers will indicate successively smaller accretion rates with the same sediment input. Thus, stability analysis made on the basis of newly established marker horizons will be biased and indicate salt marsh stabilities far above the correct level. Running...

  17. Stability analysis solutions and optical solitons in extended nonlinear Schrödinger equation with higher-order odd and even terms

    Science.gov (United States)

    Peng, Wei-Qi; Tian, Shou-Fu; Zou, Li; Zhang, Tian-Tian

    2018-01-01

    In this paper, the extended nonlinear Schrödinger equation with higher-order odd (third order) and even (fourth order) terms is investigated, whose particular cases are the Hirota equation, the Sasa-Satsuma equation and Lakshmanan-Porsezian-Daniel equation by selecting some specific values on the parameters of higher-order terms. We first study the stability analysis of the equation. Then, using the ansatz method, we derive its bright, dark solitons and some constraint conditions which can guarantee the existence of solitons. Moreover, the Ricatti equation extension method is employed to derive some exact singular solutions. The outstanding characteristics of these solitons are analyzed via several diverting graphics.

  18. Solution of second order supersymmetrical intertwining relations in Minkowski plane

    Energy Technology Data Exchange (ETDEWEB)

    Ioffe, M. V., E-mail: m.ioffe@spbu.ru; Kolevatova, E. V., E-mail: e.v.kolev@yandex.ru [Saint Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034 (Russian Federation); Nishnianidze, D. N., E-mail: cutaisi@yahoo.com [Saint Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034 (Russian Federation); Akaki Tsereteli State University, 4600 Kutaisi, Georgia (United States)

    2016-08-15

    Supersymmetrical (SUSY) intertwining relations are generalized to the case of quantum Hamiltonians in Minkowski space. For intertwining operators (supercharges) of second order in derivatives, the intertwined Hamiltonians correspond to completely integrable systems with the symmetry operators of fourth order in momenta. In terms of components, the intertwining relations correspond to the system of nonlinear differential equations which are solvable with the simplest—constant—ansatzes for the “metric” matrix in second order part of the supercharges. The corresponding potentials are built explicitly both for diagonalizable and nondiagonalizable form of “metric” matrices, and their properties are discussed.

  19. Phase stabilities of pyrite-related MTCh compounds (M=Ni, Pd, Pt; T=Si, Ge, Sn, Pb; Ch=S, Se, Te): A systematic DFT study

    International Nuclear Information System (INIS)

    Bachhuber, Frederik; Krach, Alexander; Furtner, Andrea; Söhnel, Tilo; Peter, Philipp; Rothballer, Jan; Weihrich, Richard

    2015-01-01

    Pyrite-type and related systems appear for a wide range of binary and ternary combinations of transition metals and main group elements that form Zintl type dumbbell anion units. Those representatives with 20 valence electrons exhibit an extraordinary structural flexibility and interesting properties as low-gap semiconductors or thermoelectric and electrode materials. This work is devoted to the systematic exploration of novel compounds within the class of MTCh compounds (M=Ni, Pd, Pt; T=Si, Ge, Sn, Pb; Ch=S, Se, Te) by means of density functional calculations. Their preferred structures are predicted from an extended scheme of colored pyrites and marcasites. To determine their stabilities, competing binary MT 2 and MCh 2 boundary phases are taken into account as well as ternary M 3 T 2 Ch 2 and M 2 T 3 Ch 3 systems. Recently established stability diagrams are presented to account for MTCh ordering phenomena with a focus on a not-yet-reported ordering variant of the NiAs 2 type. Due to the good agreement with experimental data available for several PtTCh systems, the predictions for the residual systems are considered sufficiently accurate. - Graphical abstract: Compositional and structural stability of MTCh compounds is investigated from first principle calculations. A conceptional approach is presented to study and predict novel stable and metastable compounds and structures of low gap semiconductors with TCh dumbbell units that are isoelectronic and structurally related to pyrite (FeS 2 ). - Highlights: • Study of compositional stability of MTCh vs. M 3 T 2 Ch 2 and M 2 T 3 Ch 3 compounds. • Study of structural stability of known and novel MTCh compounds. • Prediction of novel stable and metastable structures and compounds isoelectronic to pyrite, FeS 2

  20. Asymptotic behavior and stability of second order neutral delay differential equations

    NARCIS (Netherlands)

    Chen, G.L.; van Gaans, O.W.; Verduyn Lunel, Sjoerd

    2014-01-01

    We study the asymptotic behavior of a class of second order neutral delay differential equations by both a spectral projection method and an ordinary differential equation method approach. We discuss the relation of these two methods and illustrate some features using examples. Furthermore, a fixed

  1. Quark mass relations to four-loop order in perturbative QCD.

    Science.gov (United States)

    Marquard, Peter; Smirnov, Alexander V; Smirnov, Vladimir A; Steinhauser, Matthias

    2015-04-10

    We present results for the relation between a heavy quark mass defined in the on-shell and minimal subtraction (MS[over ¯]) scheme to four-loop order. The method to compute the four-loop on-shell integral is briefly described and the new results are used to establish relations between various short-distance masses and the MS[over ¯] quark mass to next-to-next-to-next-to-leading order accuracy. These relations play an important role in the accurate determination of the MS[over ¯] heavy quark masses.

  2. Relative energy for the Korteweg theory and related Hamiltonian flows in gas dynamics

    KAUST Repository

    Giesselmann, Jan

    2016-10-26

    For an Euler system, with dynamics generated by a potential energy functional, we propose a functional format for the relative energy and derive a relative energy identity. The latter, when applied to specific energies, yields relative energy identities for the Euler-Korteweg, the Euler-Poisson, the Quantum Hydrodynamics system, and low order approximations of the Euler-Korteweg system. For the Euler-Korteweg system we prove a stability theorem between a weak and a strong solution and an associated weak-strong uniqueness theorem. In the second part we focus on the Navier-Stokes-Korteweg system (NSK) with non-monotone pressure laws: we prove stability for the NSK system via a modified relative energy approach. We prove continuous dependence of solutions on initial data and convergence of solutions of a low order model to solutions of the NSK system. The last two results provide physically meaningful examples of how higher order regularization terms enable the use of the relative energy framework for models with energies which are not poly- or quasi-convex, but compensating via higher-order gradients.

  3. Hydrogen energy strategies and global stability and unrest

    International Nuclear Information System (INIS)

    Midilli, A.; Dincer, I.; Rosen, M.A.

    2004-01-01

    This paper focuses on hydrogen energy strategies and global stability and unrest. In order to investigate the strategic relationship between these concepts, two empirical relations that describe the effects of fossil fuels on global stability and global unrest are developed. These relations incorporate predicted utilization ratios for hydrogen energy from non-fossil fuels, and are used to investigate whether hydrogen utilization can reduce the negative global effects related to fossil fuel use, eliminate or reduce the possibilities of global energy conflicts, and contribute to achieving world stability. It is determined that, if utilization of hydrogen from non-fossil fuels increases, for a fixed usage of petroleum, coal and natural gas, the level of global unrest decreases. However, if the utilization ratio of hydrogen energy from non-fossil fuels is lower than 100%, the level of global stability decreases as the symptoms of global unrest increase. It is suggested that, to reduce the causes of global unrest and increase the likelihood of global stability in the future, hydrogen energy should be widely and efficiently used, as one component of plans for sustainable development. (author)

  4. The Application of the Accelerated Stability Assessment Program (ASAP) to Quality by Design (QbD) for Drug Product Stability

    OpenAIRE

    Waterman, Kenneth Craig

    2011-01-01

    An isoconversion paradigm, where times in different temperature and humidity-controlled stability chambers are set to provide a fixed degradant level, is shown to compensate for the complex, non-single order kinetics of solid drug products. A humidity-corrected Arrhenius equation provides reliable estimates for temperature and relative humidity effects on degradation rates. A statistical protocol is employed to determine best fits for chemical stability data, which in turn allows for accurate...

  5. Interpersonal Development, Stability, and Change in Early Adulthood

    Science.gov (United States)

    Wright, Aidan G. C.; Pincus, Aaron L.; Lenzenweger, Mark F.

    2011-01-01

    Objective This goal of this research was to explore the development of the interpersonal system mapped by the interpersonal circumplex in early adulthood (Ages 18-22). Method This study uses the Longitudinal Study of Personality Disorders sample (N = 250; 53% Female). Participants completed the Revised Interpersonal Adjective Scales (Wiggins, Trapnell, & Phillips, 1988) in their freshman, sophomore, and senior years of college. Estimates of structural, rank-order, mean, individual, and ipsative stability were calculated for the broad interpersonal dimensions of Dominance and Affiliation, and also the lower-order octant scales. Additionally, the interpersonal profile parameters of differentiation and prototypicality were calculated at each wave and explored longitudinally, and also used as predictors of interpersonal stability. Results We found excellent structural and high rank-order and ipsative stability in the interpersonal scales over this time period. Mean increases on the Affiliation axis, but not on the Dominance axis, were found to mask differential rates of change among the octant scales, along with significant individual variation in the rates of change. Interpersonal differentiation and prototypicality were related to higher stability in overall interpersonal style. Conclusions Results point to evidence of both stability and nuanced change, illuminating some of the features of the structural variables that can be derived from interpersonal circumplex profiles. PMID:22224462

  6. Synthesis and optical properties of azo -dye-attached novel second-order NLO polymers with high thermal stability

    Science.gov (United States)

    Ushiwata, Takami; Okamoto, Etsuya; Komatsu, Kyoji; Kaino, Toshikuni

    2001-06-01

    Novel second order nonlinear optical (NLO) polymethacrylate or polyacrylate polymers with high glass transition temperatures containing an azo dye attached as side-chain have been prepared using a new approach from polymethacrylic acid or polyacrylic acid as starting materials. Glass transition temperatures of 150 approximately 170 degree Celsius were obtained for Disperse red 1 dye attached polymethacrylic acid. These are attributed to the hydrogen bonding between the residual carboxyl groups in the starting polymers. Poled films by corona poling exhibited large NLO susceptibilities, (chi) (2)33 up to 53 pm/V at a wavelength of 1.3 micrometer. Due to the high glass transition temperatures of the polymers, long-term stability of the optical nonlinearity at 100 degrees Celsius was observed for 200 hrs or more. However residual carboxyl groups caused absorbance decrease mainly by hydrolysis of the ester bonds of the polymers investigated by UV-Vis absorption measurement. The stability of induced polar order of the NLO polymer was enhanced by using aminoalkyl chromophore and imidizing it thermally to introduce imide structure into the polymer main-chain. This imidized polymer exhibited (chi) (2)33 of 45 pm/V at a wavelength of 1.3 micrometer and maintained about 90% of the initial value after 230 hrs or more at 100 degrees Celsius.

  7. Stability of nonlinear waves and patterns and related topics

    Science.gov (United States)

    Ghazaryan, Anna; Lafortune, Stephane; Manukian, Vahagn

    2018-04-01

    Periodic and localized travelling waves such as wave trains, pulses, fronts and patterns of more complex structure often occur in natural and experimentally built systems. In mathematics, these objects are realized as solutions of nonlinear partial differential equations. The existence, dynamic properties and bifurcations of those solutions are of interest. In particular, their stability is important for applications, as the waves that are observable are usually stable. When the waves are unstable, further investigation is warranted of the way the instability is exhibited, i.e. the nature of the instability, and also coherent structures that appear as a result of an instability of travelling waves. A variety of analytical, numerical and hybrid techniques are used to study travelling waves and their properties. This article is part of the theme issue `Stability of nonlinear waves and patterns and related topics'.

  8. Global exponential stability of neutral high-order stochastic Hopfield neural networks with Markovian jump parameters and mixed time delays.

    Science.gov (United States)

    Huang, Haiying; Du, Qiaosheng; Kang, Xibing

    2013-11-01

    In this paper, a class of neutral high-order stochastic Hopfield neural networks with Markovian jump parameters and mixed time delays is investigated. The jumping parameters are modeled as a continuous-time finite-state Markov chain. At first, the existence of equilibrium point for the addressed neural networks is studied. By utilizing the Lyapunov stability theory, stochastic analysis theory and linear matrix inequality (LMI) technique, new delay-dependent stability criteria are presented in terms of linear matrix inequalities to guarantee the neural networks to be globally exponentially stable in the mean square. Numerical simulations are carried out to illustrate the main results. © 2013 ISA. Published by ISA. All rights reserved.

  9. Stability of Dry Probiotic Bacteria in Relation to the Cellular Membrane and Genomic DNA

    DEFF Research Database (Denmark)

    Hansen, Marie-Louise Rittermann W

    powders to infant formula and functional foods, e.g. cereal and chocolate bars. Part of production of the probiotic product often includes freeze-drying of the probiotic bacteria. Drying is necessary in the preparation of dry powders, and to increase shelf life of the product at ambient temperatures....... Freeze-drying and storage of probiotic bacteria can, however, also have a negative effect on cell stability. It is important to understand the processes, which can lead to loss of cell stability during dry storage in order to develop more stable probiotic products. The purpose of the present PhD thesis...

  10. 75 FR 65366 - Recovery Policy RP9524.2, Landslides and Slope Stability Related to Public Facilities

    Science.gov (United States)

    2010-10-22

    ...] Recovery Policy RP9524.2, Landslides and Slope Stability Related to Public Facilities AGENCY: Federal... the final Recovery Policy RP9524.2, Landslides and Slope Stability Related to Public Facilities, which... facilities threatened by landslides or slope failures; as well as the eligibility of permanent repairs to...

  11. Vorticity imbalance and stability in relation to convection

    Science.gov (United States)

    Read, W. L.; Scoggins, J. R.

    1977-01-01

    A complete synoptic-scale vorticity budget was related to convection storm development in the eastern two-thirds of the United States. The 3-h sounding interval permitted a study of time changes of the vorticity budget in areas of convective storms. Results of analyses revealed significant changes in values of terms in the vorticity equation at different stages of squall line development. Average budgets for all areas of convection indicate systematic imbalance in the terms in the vorticity equation. This imbalance resulted primarily from sub-grid scale processes. Potential instability in the lower troposphere was analyzed in relation to the development of convective activity. Instability was related to areas of convection; however, instability alone was inadequate for forecast purposes. Combinations of stability and terms in the vorticity equation in the form of indices succeeded in depicting areas of convection better than any one item separately.

  12. Topics in stability and transport in tokamaks: Dynamic transition to second stability with auxiliary heating; stability of global Alfven waves in an ignited plasma

    International Nuclear Information System (INIS)

    Fu, G.

    1988-01-01

    The problem of access to the high-beta ballooning second-stability regime by means of auxiliary heating and the problem of the stability of global-shear Alfven waves in an ignited tokamak plasma are theoretically investigated. These two problems are related to the confinement of both the bulk plasma as well as the fusion-product alpha particles an dare fundamentally important to the operation of ignited tokamak plasma. First, a model that incorporates both transport and ballooning mode stability was developed in order to estimate the auxiliary heating power required for tokamak plasma to evolve in time self-consistently into a high-beta, globally self-stabilized equilibrium. The critical heating power needed for access to second stability is found to be proportional to the square root of the anomalous diffusivity induced by the ballooning instability. Next, the full effects of toroidicity are retained in a theoretical description of global-type-shear Alfven modes whose stability can be modified by the fusion-product alpha particles that will present in an ignited tokamak plasma. Toroidicity is found to induce mode coupling and to stabilize the so-called Global Alfven Eigenmodes (GAE)

  13. Identification of the reduced order models of a BWR reactor

    International Nuclear Information System (INIS)

    Hernandez S, A.

    2004-01-01

    The present work has as objective to analyze the relative stability of a BWR type reactor. It is analyzed that so adaptive it turns out to identify the parameters of a model of reduced order so that this it reproduces a condition of given uncertainty. This will take of a real fact happened in the La Salle plant under certain operation conditions of power and flow of coolant. The parametric identification is carried out by means of an algorithm of recursive least square and an Output Error model (Output Error), measuring the output power of the reactor when the instability is present, and considering that it is produced by a change in the reactivity of the system in the same way that a sign of type step. Also it is carried out an analytic comparison of the relative stability, analyzing two types of answers: the original answer of the uncertainty of the reactor vs. the obtained response identifying the parameters of the model of reduced order, reaching the conclusion that it is very viable to adapt a model of reduced order to study the stability of a reactor, under the only condition to consider that the dynamics of the reactivity is of step type. (Author)

  14. Adaptive synchronization between two different order and topology dynamical systems

    International Nuclear Information System (INIS)

    Bowong, S.; Moukam Kakmeni, F.M.; Yamapi, R.

    2006-07-01

    This contribution studies adaptive synchronization between two dynamical systems of different order whose topological structure is also different. By order we mean the number of first order differential equations. The problem is closely related to the synchronization of strictly different systems. The master system is given by a sixth order equation with chaotic behavior whereas the slave system is a fourth-order nonautonomous with rational nonlinear terms. Based on the Lyapunov stability theory, sufficient conditions for the synchronization have been analyzed theoretically and numerically. (author)

  15. Relations between postural stability, gait and falls in elderly persons--preliminary report.

    Science.gov (United States)

    Baczkowicz, Dawid; Szczegielniak, Jan; Proszkowiec, Małgorzata

    2008-01-01

    Balance control in elderly patients is the area of interest of many researchers. The results of their studies suggest that the measurement of shifts in the centre of foot pressure on the support base (COP) can be used as a tool for identification of fall-prone persons. It is interesting whether there are any relations between functional status, gait, posture stability and the risk of falling. The aim of this study was to find the answer to this question. The study involved 20 patients (mean age 78.1+/-11.6). The functional status of the patients was evaluated according to the Barthel Index. Postural stability was assessed with the use of a Neurocom Balance Master platform. Three measurements were taken with visual feedback (eyes open-EO) and three without visual feedback (eyes closed-EC). Balance control was also evaluated with the Berg test and on the basis of the history of episodes of falling in the preceding six months. Gait was evaluated with the six-minute walking test. The parameters recorded by the force platform showed a significant relation to the values obtained in the Berg test (r=-0.60; pfalls showed a significant relation only to the EO test (r=0.4; pfalls was connected with increased body sway. 3. The functional status of the patient and the balance control evaluation according to the Berg test failed to determine the risk of falling. 4. A relation was observed between postural stability, functional status and gait.

  16. Magnetically induced crystal structure and phase stability in Fe1-cCoc

    DEFF Research Database (Denmark)

    Abrikosov, I.A.; James, P.; Eriksson, O.

    1996-01-01

    We present an ab initio determination of the crystallographic phase stability of Fe-Co alloys as a function of concentration, using the coherent potential approximation. A bcc --> hcp phase transition is found at a concentration of 85 at.% of Co, in good agreement with the experimental phase...... diagram. We demonstrate that for the Pe-rich random alloys magnetism-stabilizes the bce phase relative to the close-packed fee and hcp phases. Magnetism also favors the partially ordered alpha' phase relative to the random bce alloy. This unique relation between magnetism and phase stability for the Fe...

  17. Digital Image Stabilization Method Based on Variational Mode Decomposition and Relative Entropy

    Directory of Open Access Journals (Sweden)

    Duo Hao

    2017-11-01

    Full Text Available Cameras mounted on vehicles frequently suffer from image shake due to the vehicles’ motions. To remove jitter motions and preserve intentional motions, a hybrid digital image stabilization method is proposed that uses variational mode decomposition (VMD and relative entropy (RE. In this paper, the global motion vector (GMV is initially decomposed into several narrow-banded modes by VMD. REs, which exhibit the difference of probability distribution between two modes, are then calculated to identify the intentional and jitter motion modes. Finally, the summation of the jitter motion modes constitutes jitter motions, whereas the subtraction of the resulting sum from the GMV represents the intentional motions. The proposed stabilization method is compared with several known methods, namely, medium filter (MF, Kalman filter (KF, wavelet decomposition (MD method, empirical mode decomposition (EMD-based method, and enhanced EMD-based method, to evaluate stabilization performance. Experimental results show that the proposed method outperforms the other stabilization methods.

  18. Local order origin of thermal stability enhancement in amorphous Ag doping GeTe

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L.; Li, Y.; Yu, N. N.; Zhong, Y. P.; Miao, X. S., E-mail: miaoxs@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology (HUST), Wuhan 430074 (China); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-01-19

    We demonstrate the impacts of Ag doping on the local atomic structure of amorphous GeTe phase-change material. The variations of phonon vibrational modes, boding nature, and atomic structure are shown by Raman, X-ray photoelectron spectroscopy, and ab initio calculation. Combining the experiments and simulations, we observe that the number of Ge atoms in octahedral site decreases and that in tetrahedral site increases. This modification in local order of GeTe originating from the low valence element will affect the crystallization behavior of amorphous GeTe, which is verified by differential scanning calorimetry and transmission electron microscope results. This work not only gives the analysis on the structural change of GeTe with Ag dopants but also provides a method to enhance the thermal stability of amorphous phase-change materials for memory and brain-inspired computing applications.

  19. Modeling, Stability Analysis and Active Stabilization of Multiple DC-Microgrids Clusters

    DEFF Research Database (Denmark)

    Shafiee, Qobad; Dragicevic, Tomislav; Vasquez, Juan Carlos

    2014-01-01

    ), and more especially during interconnection with other MGs, creating dc MG clusters. This paper develops a small signal model for dc MGs from the control point of view, in order to study stability analysis and investigate effects of CPLs and line impedances between the MGs on stability of these systems....... This model can be also used to synthesis and study dynamics of control loops in dc MGs and also dc MG clusters. An active stabilization method is proposed to be implemented as a dc active power filter (APF) inside the MGs in order to not only increase damping of dc MGs at the presence of CPLs but also...... to improve their stability while connecting to the other MGs. Simulation results are provided to evaluate the developed models and demonstrate the effectiveness of proposed active stabilization technique....

  20. Nonlinear feedback synchronisation control between fractional-order and integer-order chaotic systems

    International Nuclear Information System (INIS)

    Jia Li-Xin; Dai Hao; Hui Meng

    2010-01-01

    This paper focuses on the synchronisation between fractional-order and integer-order chaotic systems. Based on Lyapunov stability theory and numerical differentiation, a nonlinear feedback controller is obtained to achieve the synchronisation between fractional-order and integer-order chaotic systems. Numerical simulation results are presented to illustrate the effectiveness of this method

  1. Linear stability analysis of flow instabilities with a nodalized reduced order model in heated channel

    International Nuclear Information System (INIS)

    Paul, Subhanker; Singh, Suneet

    2015-01-01

    The prime objective of the presented work is to develop a Nodalized Reduced Order Model (NROM) to carry linear stability analysis of flow instabilities in a two-phase flow system. The model is developed by dividing the single phase and two-phase region of a uniformly heated channel into N number of nodes followed by time dependent spatial linear approximations for single phase enthalpy and two-phase quality between the consecutive nodes. Moving boundary scheme has been adopted in the model, where all the node boundaries vary with time due to the variation of boiling boundary inside the heated channel. Using a state space approach, the instability thresholds are delineated by stability maps plotted in parameter planes of phase change number (N pch ) and subcooling number (N sub ). The prime feature of the present model is that, though the model equations are simpler due to presence of linear-linear approximations for single phase enthalpy and two-phase quality, yet the results are in good agreement with the existing models (Karve [33]; Dokhane [34]) where the model equations run for several pages and experimental data (Solberg [41]). Unlike the existing ROMs, different two-phase friction factor multiplier correlations have been incorporated in the model. The applicability of various two-phase friction factor multipliers and their effects on stability behaviour have been depicted by carrying a comparative study. It is also observed that the Friedel model for friction factor calculations produces the most accurate results with respect to the available experimental data. (authors)

  2. Topics in numerical relativity : the periodic standing-wave approximation, the stability of constraints in free evolution, and the spin of dynamical black holes

    Science.gov (United States)

    Owen, Robert

    This thesis concerns numerical relativity, the attempt to study Einstein's theory of gravitation using numerical discretization. The goal of the field, the study of gravitational dynamics in cases where symmetry reduction or perturbation theory are not possible, finally seems to be coming to fruition, at least for the archetypal problem of the inspiral and coalescence of binary black hole systems. This thesis presents three episodes that each bear some relationship to this story.Chapters 2 and 3 present previously published work in collaboration with Richard Price and others on the so-called periodic standing-wave (PSW) approximation for binary inspiral. The approximation is to balance outgoing radiation with incoming radiation, stabilizing the orbit and making the problem stationary in a rotating frame. Chapters 2 and 3 apply the method to the problem of co-orbiting charges coupled to a nonlinear scalar field in three dimensions.Chapters 4, 5, and 6 concern the stability of constraint fields in conventional numerical relativity simulations. Chapter 4 (also previously published work, in collaboration with the Caltech numerical relativity group, along with Michael Holst and Lawrence Kidder) presents a method for immediately correcting violations of constraints after they have arisen. Chapters 5 and 6 present methods to ``damp' away constraint violations dynamically in two specific contexts. Chapter 5 (previously published work in collaboration with the Caltech numerical relativity group and Lawrence Kidder) presents a first-order linearly degenerate symmetric hyperbolic representation of Einstein's equations in generalized harmonic gauge. A representation is presented that stabilizes all constraints, including those that appear when the system is written in first-order form. Chapter 6 presents a generalization of the Kidder-Scheel-Teukolsky evolution systems that provides much-improved stability. This is investigated with numerical simulations of a single black hole

  3. Moral Judgment and Its Relation to Second-Order Theory of Mind

    Science.gov (United States)

    Fu, Genyue; Xiao, Wen S.; Killen, Melanie; Lee, Kang

    2014-01-01

    Recent research indicates that moral judgment and 1st-order theory of mind abilities are related. What is not known, however, is how 2nd-order theory of mind is related to moral judgment. In the present study, we extended previous findings by administering a morally relevant theory of mind task (an accidental transgressor) to 4- to 7-year-old…

  4. Moral judgment and its relation to second-order theory of mind.

    Science.gov (United States)

    Fu, Genyue; Xiao, Wen S; Killen, Melanie; Lee, Kang

    2014-08-01

    Recent research indicates that moral judgment and 1st-order theory of mind abilities are related. What is not known, however, is how 2nd-order theory of mind is related to moral judgment. In the present study, we extended previous findings by administering a morally relevant theory of mind task (an accidental transgressor) to 4- to 7-year-old Chinese children (N = 79) and analyzing connections with 2nd-order theory of mind understanding. Using hierarchical multiple regression analyses, we found that above and beyond age, children's 1st-order theory of mind and 2nd-order theory of mind each significantly and uniquely contributed to children's moral evaluations of the intention in the accidental transgression. These findings highlight the important roles that 1st- and 2nd-order theory of mind play in leading children to make appropriate moral judgments based on an actor's intention in a social situation. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  5. Stability analysis of fuzzy parametric uncertain systems.

    Science.gov (United States)

    Bhiwani, R J; Patre, B M

    2011-10-01

    In this paper, the determination of stability margin, gain and phase margin aspects of fuzzy parametric uncertain systems are dealt. The stability analysis of uncertain linear systems with coefficients described by fuzzy functions is studied. A complexity reduced technique for determining the stability margin for FPUS is proposed. The method suggested is dependent on the order of the characteristic polynomial. In order to find the stability margin of interval polynomials of order less than 5, it is not always necessary to determine and check all four Kharitonov's polynomials. It has been shown that, for determining stability margin of FPUS of order five, four, and three we require only 3, 2, and 1 Kharitonov's polynomials respectively. Only for sixth and higher order polynomials, a complete set of Kharitonov's polynomials are needed to determine the stability margin. Thus for lower order systems, the calculations are reduced to a large extent. This idea has been extended to determine the stability margin of fuzzy interval polynomials. It is also shown that the gain and phase margin of FPUS can be determined analytically without using graphical techniques. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

  6. The relative worst order ratio applied to paging

    DEFF Research Database (Denmark)

    Boyar, Joan; Favrholdt, Lene Monrad; Larsen, Kim Skak

    2007-01-01

    The relative worst order ratio, a new measure for the quality of on-line algorithms, was recently defined and applied to two bin packing problems. Here, we apply it to the paging problem and obtain the following results: We devise a new deterministic paging algorithm, Retrospective-LRU, and show...

  7. Age-related changes in visual temporal order judgment performance: Relation to sensory and cognitive capacities.

    Science.gov (United States)

    Busey, Thomas; Craig, James; Clark, Chris; Humes, Larry

    2010-08-06

    Five measures of temporal order judgments were obtained from 261 participants, including 146 elder, 44 middle aged, and 71 young participants. Strong age group differences were observed in all five measures, although the group differences were reduced when letter discriminability was matched for all participants. Significant relations were found between these measures of temporal processing and several cognitive and sensory assays, and structural equation modeling revealed the degree to which temporal order processing can be viewed as a latent factor that depends in part on contributions from sensory and cognitive capacities. The best-fitting model involved two different latent factors representing temporal order processing at same and different locations, and the sensory and cognitive factors were more successful predicting performance in the different location factor than the same-location factor. Processing speed, even measured using high-contrast symbols on a paper-and-pencil test, was a surprisingly strong predictor of variability in both latent factors. However, low-level sensory measures also made significant contributions to the latent factors. The results demonstrate the degree to which temporal order processing relates to other perceptual and cognitive capacities, and address the question of whether age-related declines in these capacities share a common cause. Copyright 2010 Elsevier Ltd. All rights reserved.

  8. The role of intrinsic muscle properties for stable hopping-stability is achieved by the force-velocity relation

    International Nuclear Information System (INIS)

    Haeufle, D F B; Grimmer, S; Seyfarth, A

    2010-01-01

    A reductionist approach was presented to investigate which level of detail of the physiological muscle is required for stable locomotion. Periodic movements of a simplified one-dimensional hopping model with a Hill-type muscle (one contractile element, neither serial nor parallel elastic elements) were analyzed. Force-length and force-velocity relations of the muscle were varied in three levels of approximation (constant, linear and Hill-shaped nonlinear) resulting in nine different hopping models of different complexity. Stability of these models was evaluated by return map analysis and the performance by the maximum hopping height. The simplest model (constant force-length and constant force-velocity relations) outperformed all others in the maximum hopping height but was unstable. Stable hopping was achieved with linear and Hill-shaped nonlinear characteristic of the force-velocity relation. The characteristics of the force-length relation marginally influenced hopping stability. The results of this approach indicate that the intrinsic properties of the contractile element are responsible for stabilization of periodic movements. This connotes that (a) complex movements like legged locomotion could benefit from stabilizing effects of muscle properties, and (b) technical systems could benefit from the emerging stability when implementing biological characteristics into artificial muscles.

  9. Island of stability for consistent deformations of Einstein's gravity.

    Science.gov (United States)

    Berkhahn, Felix; Dietrich, Dennis D; Hofmann, Stefan; Kühnel, Florian; Moyassari, Parvin

    2012-03-30

    We construct deformations of general relativity that are consistent and phenomenologically viable, since they respect, in particular, cosmological backgrounds. These deformations have unique symmetries in accordance with their Minkowski cousins (Fierz-Pauli theory for massive gravitons) and incorporate a background curvature induced self-stabilizing mechanism. Self-stabilization is essential in order to guarantee hyperbolic evolution in and unitarity of the covariantized theory, as well as the deformation's uniqueness. We show that the deformation's parameter space contains islands of absolute stability that are persistent through the entire cosmic evolution.

  10. Studies of thermodynamic properties and relative stability of a series of polyfluorinated dibenzo-p-dioxins by density functional theory

    International Nuclear Information System (INIS)

    Yang Xi; Liu Hui; Hou Haifeng; Flamm, Alison; Zhang Xuesheng; Wang Zunyao

    2010-01-01

    The thermodynamic properties of 75 polyfluorinated dibenzo-p-dioxins (PFDDs) in the ideal gas state at 298.15 K and 1.013 x 10 5 Pa have been calculated at the B3LYP/6-311G* level using Gaussian 03 program. The isodesmic reactions were designed to calculate standard enthalpy of formation (ΔH f o ) and standard free energy of formation (ΔG f o ) of PFDDs congeners. The relations of these thermodynamic parameters with the number and position of fluorine atom substitution (N PFS ) were discussed, and it was found that there exist high correlations between thermodynamic parameters (entropy (S o ), ΔH f o and ΔG f o ) and N PFS . According to the relative magnitude of their ΔG f o , the relative stability order of PFDD congeners was theoretically proposed.

  11. Stability improvement for coil position locking of joule balance

    Science.gov (United States)

    Bai, Yang; Liu, Yongmeng; Lu, Yunfeng; Hu, Pengcheng; Wang, Dawei; Li, Zhengkun; Tan, Jiubin; Zhang, Zhonghua

    2017-08-01

    The relative vertical position locking precision between the exciting and suspended coils is an important uncertainty for the Planck constant traceability in joule balance. In order to improve the relative vertical position locking precision, several stability experiments are conducted. The stability characteristics of the suspended and exciting coils are measured using a six-axis laser interferometer system; meanwhile, the effectiveness of the active vibration isolation table is measured using a vibration measurement sensor. The piezoelectric ceramic actuators with PID controller are used to compensate the relative vertical displacement drifts while a six-axis laser interferometer system is used to measure the positions of two coils. Experimental results show that the relative vertical position is stably locked.

  12. Stability of medium range order in Al-based metallic glass compacted by severe plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Kovács, Zs.; Henits, P. [Department of Materials Physics, Eötvös University, P.O.B. 32, H-1518 Budapest (Hungary); Varga, L.K. [Research Institute for Solid state Physics and Optics, Hungarian Academy of Sciences, P.O.B. 49, H-1525 Budapest (Hungary); Schafler, E. [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, A-1090 Vienna (Austria); Révész, Á., E-mail: reveszadam@ludens.elte.hu [Department of Materials Physics, Eötvös University, P.O.B. 32, H-1518 Budapest (Hungary)

    2013-06-05

    Highlights: ► High pressure torsion has been applied to produce low-porosity bulk Al-based amorphous specimens. ► The compacted disks possess higher hardness than the original glass. ► Mechanical and thermal impacts have only minor effects on the glassy structure. ► Medium range order is an inherent feature of the amorphous state. -- Abstract: High pressure torsion has successfully been applied to produce low-porosity, bulk specimens from Al-based metallic glass ribbons (Al{sub 85}Y{sub 8}Ni{sub 5}Co{sub 2}, Al{sub 85}Ce{sub 8}Ni{sub 5}Co{sub 2} and Al{sub 85}Gd{sub 8}Ni{sub 5}Co{sub 2}). The compacted disks possess higher hardness than the original glass and have substantial glass fraction with nanocrystalline precipitations. Mechanical and thermal impacts have only minor effects on the glassy structure as demonstrated by the stability of the X-ray diffraction halo positions. Unchanged halos reveal that medium range order is a key characteristic of the amorphous state.

  13. Low temperature stabilization process for production of carbon fiber having structural order

    Science.gov (United States)

    Rios, Orlando; McGuire, Michael Alan; More, Karren Leslie; Tenhaeff, Wyatt Evan; Menchhofer, Paul A.; Paulauskas, Felix Leonard

    2017-08-15

    A method for producing a carbon fiber, the method comprising: (i) subjecting a continuous carbon fiber precursor having a polymeric matrix in which strength-enhancing particles are incorporated to a stabilization process during which the carbon fiber precursor is heated to within a temperature range ranging from the glass transition temperature to no less than 20.degree. C. below the glass transition temperature of the polymeric matrix, wherein the maximum temperature employed in the stabilization process is below 400.degree. C., for a processing time within said temperature range of at least 1 hour in the presence of oxygen and in the presence of a magnetic field of at least 1 Tesla, while said carbon fiber precursor is held under an applied axial tension; and (ii) subjecting the stabilized carbon fiber precursor, following step (i), to a carbonization process. The stabilized carbon fiber precursor, resulting carbon fiber, and articles made thereof are also described.

  14. Standard Model Vacuum Stability and Weyl Consistency Conditions

    DEFF Research Database (Denmark)

    Antipin, Oleg; Gillioz, Marc; Krog, Jens

    2013-01-01

    At high energy the standard model possesses conformal symmetry at the classical level. This is reflected at the quantum level by relations between the different beta functions of the model. These relations are known as the Weyl consistency conditions. We show that it is possible to satisfy them...... order by order in perturbation theory, provided that a suitable coupling constant counting scheme is used. As a direct phenomenological application, we study the stability of the standard model vacuum at high energies and compare with previous computations violating the Weyl consistency conditions....

  15. Water-stability of soil aggregates in relation to selected properties

    International Nuclear Information System (INIS)

    Mbagwu, J.S.C.; Bazzoffi, P.; Unamba Oparah, I.

    1995-03-01

    The stability of soil aggregates in water is an important soil physical property for evaluating the potential of agricultural soils to erode and elucidating the mechanisms of soil erosion. In this study we used aggregates from 15 surface soil samples in Italy to evaluate the influence of intrinsic soil physical, chemical and mineralogical properties on aggregates stability (AS). The aim was to develop a model for predicting AS from a subset of these soil properties. The index of stability used is the mean-weight diameter of water-stable aggregates (MWD). The model developed with soil physical properties alone explained just 42% of variance in MWD and predicted AS in only 20% of test soils. The model developed with mineralogical properties alone explained 70% of variance in MWD and predicted AS in 60% of the test soils. The chemical properties - based model explained 90% of variance in MWD and predicted AS in 80% of the test soils. The best-fit model was developed with soil properties from the physical, chemical and mineralogical subsets. It explained 98% of variance in MWD and predicted AS in 100% of the test soils. This model shows that the most important soil properties which influence the AS of these soils include ratio of total sand to clay, concentrations of iron oxide, magnesium oxide, organic matter, silica/alumina ratio, chlorite, feldspar and muscovite. This indicates that fairly good estimates of the relative stability of these aggregates in water and hence of their potential to erode, requires a knowledge of the physico-chemical and mineralogical properties. (author). 40 refs, 4 tabs

  16. A Methodological Study of Order Effects in Reporting Relational Aggression Experiences.

    Science.gov (United States)

    Serico, Jennifer M; NeMoyer, Amanda; Goldstein, Naomi E S; Houck, Mark; Leff, Stephen S

    2018-03-01

    Unlike the overt nature of physical aggression, which lends itself to simpler and more direct methods of investigation, the often-masked nature of relational aggression has led to difficulties and debate regarding the most effective tools of study. Given concerns with the accuracy of third-party relational aggression reports, especially as individuals age, self-report measures may be particularly useful when assessing experiences with relational aggression. However, it is important to recognize validity concerns-in particular, the potential effects of item order presentation-associated with self-report of relational aggression perpetration and victimization. To investigate this issue, surveys were administered and completed by 179 young adults randomly assigned to one of four survey conditions reflecting manipulation of item order. Survey conditions included presentation of (a) perpetration items only, (b) victimization items only, (c) perpetration items followed by victimization items, and (d) victimization items followed by perpetration items. Results revealed that participants reported perpetrating relational aggression significantly more often when asked only about perpetration or when asked about perpetration before victimization, compared with participants who were asked about victimization before perpetration. Item order manipulation did not result in significant differences in self-reported victimization experiences. Results of this study indicate a need for greater consideration of item order when conducting research using self-report data and the importance of additional investigation into which form of item presentation elicits the most accurate self-report information.

  17. Robust Adaptive Stabilization of Linear Time-Invariant Dynamic Systems by Using Fractional-Order Holds and Multirate Sampling Controls

    Directory of Open Access Journals (Sweden)

    S. Alonso-Quesada

    2010-01-01

    Full Text Available This paper presents a strategy for designing a robust discrete-time adaptive controller for stabilizing linear time-invariant (LTI continuous-time dynamic systems. Such systems may be unstable and noninversely stable in the worst case. A reduced-order model is considered to design the adaptive controller. The control design is based on the discretization of the system with the use of a multirate sampling device with fast-sampled control signal. A suitable on-line adaptation of the multirate gains guarantees the stability of the inverse of the discretized estimated model, which is used to parameterize the adaptive controller. A dead zone is included in the parameters estimation algorithm for robustness purposes under the presence of unmodeled dynamics in the controlled dynamic system. The adaptive controller guarantees the boundedness of the system measured signal for all time. Some examples illustrate the efficacy of this control strategy.

  18. Relation between Feynman Cycles and Off-Diagonal Long-Range Order

    International Nuclear Information System (INIS)

    Ueltschi, Daniel

    2006-01-01

    The usual order parameter for Bose-Einstein condensation involves the off-diagonal correlation function of Penrose and Onsager, but an alternative is Feynman's notion of infinite cycles. We present a formula that relates both order parameters. We discuss its validity with the help of rigorous results and heuristic arguments. The conclusion is that infinite cycles do not always represent the Bose condensate

  19. Bisindeno-annulated pentacenes with exceptionally high photo-stability and ordered molecular packing: Simple synthesis by a regio-selective Scholl reaction

    KAUST Repository

    Naibi Lakshminarayana, Arun; Chang, Jingjing; Luo, Jie; Zheng, Bin; Huang, Kuo-Wei; Chi, Chunyan

    2015-01-01

    Bisindeno-annulated pentacenes 3a and 3b were synthesized by a simple regio-selective, FeCl3-mediated Scholl reaction from the corresponding 6,13-diaryl pentacene precursors. The fusion of two indeno-units dramatically changes the electronic properties and chemical reactivity of pentacene and the obtained compounds exhibited exceptionally high photo-stability in the solution, with a half-life time of 11.2 (3a) and 32.0 (3b) days under ambient light and air conditions. Ordered molecular packing with a small π-π stacking distance was observed in the single crystals of 3a and 3b. Our research provides a promising strategy to access stable higher order acenes with controlled molecular order. This journal is

  20. Order through disorder: hyper-mobile C-terminal residues stabilize the folded state of a helical peptide. a molecular dynamics study.

    Directory of Open Access Journals (Sweden)

    Kalliopi K Patapati

    Full Text Available Conventional wisdom has it that the presence of disordered regions in the three-dimensional structures of polypeptides not only does not contribute significantly to the thermodynamic stability of their folded state, but, on the contrary, that the presence of disorder leads to a decrease of the corresponding proteins' stability. We have performed extensive 3.4 µs long folding simulations (in explicit solvent and with full electrostatics of an undecamer peptide of experimentally known helical structure, both with and without its disordered (four residue long C-terminal tail. Our simulations clearly indicate that the presence of the apparently disordered (in structural terms C-terminal tail, increases the thermodynamic stability of the peptide's folded (helical state. These results show that at least for the case of relatively short peptides, the interplay between thermodynamic stability and the apparent structural stability can be rather subtle, with even disordered regions contributing significantly to the stability of the folded state. Our results have clear implications for the understanding of peptide energetics and the design of foldable peptides.

  1. Extrapolated stabilized explicit Runge-Kutta methods

    Science.gov (United States)

    Martín-Vaquero, J.; Kleefeld, B.

    2016-12-01

    Extrapolated Stabilized Explicit Runge-Kutta methods (ESERK) are proposed to solve multi-dimensional nonlinear partial differential equations (PDEs). In such methods it is necessary to evaluate the function nt times per step, but the stability region is O (nt2). Hence, the computational cost is O (nt) times lower than for a traditional explicit algorithm. In that way stiff problems can be integrated by the use of simple explicit evaluations in which case implicit methods usually had to be used. Therefore, they are especially well-suited for the method of lines (MOL) discretizations of parabolic nonlinear multi-dimensional PDEs. In this work, first s-stages first-order methods with extended stability along the negative real axis are obtained. They have slightly shorter stability regions than other traditional first-order stabilized explicit Runge-Kutta algorithms (also called Runge-Kutta-Chebyshev codes). Later, they are used to derive nt-stages second- and fourth-order schemes using Richardson extrapolation. The stability regions of these fourth-order codes include the interval [ - 0.01nt2, 0 ] (nt being the number of total functions evaluations), which are shorter than stability regions of ROCK4 methods, for example. However, the new algorithms neither suffer from propagation of errors (as other Runge-Kutta-Chebyshev codes as ROCK4 or DUMKA) nor internal instabilities. Additionally, many other types of higher-order (and also lower-order) methods can be obtained easily in a similar way. These methods also allow adaptation of the length step with no extra cost. Hence, the stability domain is adapted precisely to the spectrum of the problem at the current time of integration in an optimal way, i.e., with minimal number of additional stages. We compare the new techniques with other well-known algorithms with good results in very stiff diffusion or reaction-diffusion multi-dimensional nonlinear equations.

  2. ICRF stabilization of sawteeth on TFTR

    International Nuclear Information System (INIS)

    Phillips, C.K.; Hosea, J.; Stevens, J.; Wilson, J.R.; Bell, M.; Bitter, M.; Cheng, C.Z.; Darrow, D.; Fredrickson, E.; Hammett, G.W.; Hill, K.; Hsuan, H.; Jassby, D.; McCune, D.; McGuire, K.; Owens, D.K.; Park, H.; Ramsey, A.; Schilling, G.; Schivell, J.; Stratton, B.; Synakowski, E.; Taylor, G.; Towner, H.; White, R.; Zweben, S.; Phillips, M.W.; Hughes, M.; Bush, C.; Goldfinger, R.; Hoffman, D.; Houlberg, W.; Nagayama, Y.; Smithe, D.N.

    1992-01-01

    Results obtained from experiments utilizing high power ICRF (ion cyclotron range of frequency) heating to stabilize sawtooth oscillations on TFTR are reviewed. The key observations include existence of a minimum ICRF power required to achieve stabilization, a dependence of the stabilization threshold on the relative size of the ICRF power deposition profile to the q=1 volume, and a peaking of the equilibrium pressure and current profiles during sawtooth-free phases of the discharges. In addition, preliminary measurements of the poloidal magnetic field profile indicate that q on axis decreases to a value of 0.55±0.15 after a sawtooth-stabilized period of ∼0.5 sec has transpired. The results are discussed in the context of theory, which suggests that the fast ions produced by the ICRF heating suppress sawteeth by stabilizing the m=1 MHD instabilities believed to be the trigger for the sawtooth oscillations. Though qualitative agreement is found between the observations and the theory, further refinement of the theory coupled with more accurate measurements of experimental profiles will be required in order to complete quantitative comparisons

  3. Ballooning mode stabilization by moderate sheared rotation

    International Nuclear Information System (INIS)

    Hameiri, E.

    1996-01-01

    Sheared toroidal plasma rotation has been known for some time to have a stabilizing effect on the ballooning modes. A recent calculation showed that a large flow shear, with dΩ/dq of the order of the Alfven toroidal frequency, can stabilize the ballooning modes. This latest result is, in fact, not so optimistic. For observed flows with Mach number of order unity one gets dΩ/dq smaller by a factor O(√β) from the required level (if the flow shear length is of the same order as the magnetic shear length). Moreover, the calculation does not take into account a possibly large transient growth of the mode amplitude due to its Floquet structures We show here that, in fact, there is a general tendency of the ballooning mode to stabilize as soon as the flow shear dΩ/dq exceeds the (O√β smaller) open-quotes slowclose quotes magnetosonic wave frequency. Our analysis is perturbative, where the small parameter is related to the small coupling between the slow and Alfven waves-as is the case in a high aspect-ratio tokamak. (In the perturbation it is important to take the Hamiltonian nature of the governing equations into account.) Moreover, our results apply to the relevant transient growth of the mode amplitude

  4. Advanced techniques for the analysis of crisis stability, deterrence, and latency

    Energy Technology Data Exchange (ETDEWEB)

    Canavan, G.H.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The principal results of studies on crisis stability, deterrence, and latency are presented in their order of development. They capture the main features of stability analysis; relate first strike, crisis, and arms control stability as seen from US and Russian perspective; and address whether different metrics, uncertain damage preferences, or the deployment of defenses can be destabilizing. The report explores differences between unilateral and proportional force reductions in the region of deep reductions where concern shifts from stability to latency.

  5. Relational motivation for conformal operator ordering in quantum cosmology

    International Nuclear Information System (INIS)

    Anderson, Edward

    2010-01-01

    Operator ordering in quantum cosmology is a major as-yet unsettled ambiguity with not only formal but also physical consequences. We determine the Lagrangian origin of the conformal invariance that underlies the conformal operator-ordering choice in quantum cosmology. This arises particularly naturally and simply from relationalist product-type actions (such as the Jacobi action for mechanics or Baierlein-Sharp-Wheeler-type actions for general relativity), for which all that is required is for the kinetic and potential factors to rescale in compensation to each other. These actions themselves mathematically sharply implement philosophical principles relevant to whole-universe modelling, so that the motivation for conformal operator ordering in quantum cosmology is thereby substantially strengthened. Relationalist product-type actions also give emergent times which amount to recovering Newtonian, proper and cosmic time in various contexts. The conformal scaling of these actions directly tells us how emergent time scales; if one follows suit with the Newtonian time or the lapse in the more commonly used difference-type Euler-Lagrange or Arnowitt-Deser-Misner-type actions, one sees how these too obey a more complicated conformal invariance. Moreover, our discovery of the conformal scaling of the emergent time permits relating how this simplifies equations of motion with how affine parametrization simplifies geodesics.

  6. Estrogen-related receptor α decreases RHOA stability to induce orientated cell migration.

    Science.gov (United States)

    Sailland, Juliette; Tribollet, Violaine; Forcet, Christelle; Billon, Cyrielle; Barenton, Bruno; Carnesecchi, Julie; Bachmann, Alice; Gauthier, Karine Cécile; Yu, Shan; Giguère, Vincent; Chan, Franky L; Vanacker, Jean-Marc

    2014-10-21

    Several physiopathological processes require orientated cellular migration. This phenomenon highly depends on members of the RHO family of GTPases. Both excessive and deficient RHO activity impair directional migration. A tight control is thus exerted on these proteins through the regulation of their activation and of their stability. Here we show that the estrogen-related receptor α (ERRα) directly activates the expression of TNFAIP1, the product of which [BTB/POZ domain-containing adapter for Cullin3-mediated RhoA degradation 2 (BACURD2)] regulates RHOA protein turnover. Inactivation of the receptor leads to enhanced RHOA stability and activation. This results in cell disorientation, increased actin network, and inability to form a lamellipodium at the migration edge. As a consequence, directional migration, but not cell motility per se, is impaired in the absence of the receptor, under pathological as well as physiological conditions. Altogether, our results show that the control exerted by ERRα on RHOA stability is required for directional migration.

  7. Relative boundedness and compactness theory for second-order differential operators

    Directory of Open Access Journals (Sweden)

    Don B. Hinton

    1997-01-01

    Full Text Available The problem considered is to give necessary and sufficient conditions for perturbations of a second-order ordinary differential operator to be either relatively bounded or relatively compact. Such conditions are found for three classes of operators. The conditions are expressed in terms of integral averages of the coefficients of the perturbing operator.

  8. Geological hazards investigation - relative slope stability map

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dae Suk; Kim, Won Young; Yu, Il Hyon; Kim, Kyeong Su; Lee, Sa Ro; Choi, Young Sup [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1997-12-01

    The Republic of Korea is a mountainous country; the mountains occupy about three quarters of her land area, an increasing urban development being taken place along the mountainside. For the reason, planners as well as developers and others must realize that some of the urban areas may be threaten by geologic hazards such as landslides and accelerated soil and rock creeps. For the purpose of environmental land-use planning, a mapping project on relative slope-stability was established in 1996. The selected area encompasses about 5,900 km{sup 2} including the topographic maps of Ulsan, Yongchon, Kyongju, Pulguksa, and Kampo, all at a scale of 1:50,000. Many disturbed and undisturbed soil samples, which were collected from the ares of the landslides and unstable slopes, were tested for their physical properties and shear strength. They were classified as GC, SP, SC, SM, SP-SM, SC-SM, CL, ML, and MH according to the Unified Soil Classification System, their liquid limit and plasticity index ranging from 25.3% to as high as 81.3% and from 4.1% to 41.5%, respectively. X-ray analysis revealed that many of the soils contained a certain amount of montmorillonite. Based on the available information as well as both field and laboratory investigation, it was found out that the most common types of slope failures in the study area were both debris and mud flows induced by the heavy rainfalls during the period of rainy season; the flows mostly occurred in the colluvial deposits at the middle and foot of mountains. Thus the deposits generally appear to be the most unstable slope forming materials in the study area. Produced for the study area were six different maps consisting of slope classification map, soil classification map, lineament density map, landslide distribution map, zonal map of rainfall, and geology map, most of them being stored as data base. Using the first four maps and GIS, two sheets of relative slope-stability maps were constructed, each at a scale of 1

  9. Figure-ground processing during fixational saccades in V1: indication for higher-order stability.

    Science.gov (United States)

    Gilad, Ariel; Pesoa, Yair; Ayzenshtat, Inbal; Slovin, Hamutal

    2014-02-26

    In a typical visual scene we continuously perceive a "figure" that is segregated from the surrounding "background" despite ongoing microsaccades and small saccades that are performed when attempting fixation (fixational saccades [FSs]). Previously reported neuronal correlates of figure-ground (FG) segregation in the primary visual cortex (V1) showed enhanced activity in the "figure" along with suppressed activity in the noisy "background." However, it is unknown how this FG modulation in V1 is affected by FSs. To investigate this question, we trained two monkeys to detect a contour embedded in a noisy background while simultaneously imaging V1 using voltage-sensitive dyes. During stimulus presentation, the monkeys typically performed 1-3 FSs, which displaced the contour over the retina. Using eye position and a 2D analytical model to map the stimulus onto V1, we were able to compute FG modulation before and after each FS. On the spatial cortical scale, we found that, after each FS, FG modulation follows the stimulus retinal displacement and "hops" within the V1 retinotopic map, suggesting visual instability. On the temporal scale, FG modulation is initiated in the new retinotopic position before it disappeared from the old retinotopic position. Moreover, the FG modulation developed faster after an FS, compared with after stimulus onset, which may contribute to visual stability of FG segregation, along the timeline of stimulus presentation. Therefore, despite spatial discontinuity of FG modulation in V1, the higher-order stability of FG modulation along time may enable our stable and continuous perception.

  10. Personality traits in old age: measurement and rank-order stability and some mean-level change.

    Science.gov (United States)

    Mõttus, René; Johnson, Wendy; Deary, Ian J

    2012-03-01

    Lothian Birth Cohorts, 1936 and 1921 were used to study the longitudinal comparability of Five-Factor Model (McCrae & John, 1992) personality traits from ages 69 to 72 years and from ages 81 to 87 years, and cross-cohort comparability between ages 69 and 81 years. Personality was measured using the 50-item International Personality Item Pool (Goldberg, 1999). Satisfactory measurement invariance was established across time and cohorts. High rank-order stability was observed in both cohorts. Almost no mean-level change was observed in the younger cohort, whereas Extraversion, Agreeableness, Conscientiousness, and Intellect declined significantly in the older cohort. The older cohort scored higher on Agreeableness and Conscientiousness. In these cohorts, individual differences in personality traits continued to be stable even in very old age, mean-level changes accelerated.

  11. Geometrical optics in general relativity: A study of the higher order corrections

    International Nuclear Information System (INIS)

    Anile, A.M.

    1976-01-01

    The higher order corrections to geometrical optics are studied in general relativity for an electromagnetic test wave. An explicit expression is found for the average energy--momentum tensor which takes into account the first-order corrections. Finally the first-order corrections to the well-known area-intensity law of geometrical optics are derived

  12. Thematic orders and the comprehension of subject-extracted relative clauses in Mandarin Chinese

    Directory of Open Access Journals (Sweden)

    Chien-Jer Charles Lin

    2015-09-01

    Full Text Available This study investigates the comprehension of three kinds of subject-extracted relative clauses (SRs in Mandarin Chinese: standard SRs, relative clauses involving the disposal ba construction (‘disposal SRs’, and relative clauses involving the long passive bei constructions (‘passive SRs’. In a self-paced reading experiment, the regions before the relativizer (where the sentential fragments are temporarily ambiguous showed reading patterns consistent with expectation-based incremental processing: standard SRs (with the highest constructional frequency and the least complex syntactic structure were processed faster than the other two variants. However, in the regions after the relativizer and the head noun (where the existence of a relative clause is unambiguously indicated, a top-down global effect of thematic ordering was observed: passive SRs (whose thematic role order conforms to the canonical thematic order of Chinese were read faster than both the standard SRs and the disposal SRs. Taken together, these results suggest that two expectation-based processing factors are involved in the comprehension of Chinese relative clauses, including both the structural probabilities of pre-relativizer constituents and the overall surface thematic orders in the relative clauses.

  13. Analysis on soil compressibility changes of samples stabilized with lime

    Directory of Open Access Journals (Sweden)

    Elena-Andreea CALARASU

    2016-12-01

    Full Text Available In order to manage and control the stability of buildings located on difficult foundation soils, several techniques of soil stabilization were developed and applied worldwide. Taking into account the major significance of soil compressibility on construction durability and safety, the soil stabilization with a binder like lime is considered one of the most used and traditional methods. The present paper aims to assess the effect of lime content on soil geotechnical parameters, especially on compressibility ones, based on laboratory experimental tests, for several soil categories in admixture with different lime dosages. The results of this study indicate a significant improvement of stabilized soil parameters, such as compressibility and plasticity, in comparison with natural samples. The effect of lime stabilization is related to an increase of soil structure stability by increasing the bearing capacity.

  14. Control and Synchronization of the Fractional-Order Lorenz Chaotic System via Fractional-Order Derivative

    Directory of Open Access Journals (Sweden)

    Ping Zhou

    2012-01-01

    Full Text Available The unstable equilibrium points of the fractional-order Lorenz chaotic system can be controlled via fractional-order derivative, and chaos synchronization for the fractional-order Lorenz chaotic system can be achieved via fractional-order derivative. The control and synchronization technique, based on stability theory of fractional-order systems, is simple and theoretically rigorous. The numerical simulations demonstrate the validity and feasibility of the proposed method.

  15. Film Grain-Size Related Long-Term Stability of Inverted Perovskite Solar Cells.

    Science.gov (United States)

    Chiang, Chien-Hung; Wu, Chun-Guey

    2016-09-22

    The power conversion efficiency (PCE) of the perovskite solar cell is high enough to be commercially viable. The next important issue is the stability of the device. This article discusses the effect of the perovskite grain-size on the long-term stability of inverted perovskite solar cells. Perovskite films composed of various sizes of grains were prepared by controlling the solvent annealing time. The grain-size related stability of the inverted cells was investigated both in ambient atmosphere at relative humidity of approximately 30-40 % and in a nitrogen filled glove box (H 2 Operovskite film having the grain size larger than 1 μm (D-10) decreases less than 10 % with storage in a glove box and less than 15 % when it was stored under an ambient atmosphere for 30 days. However, the cell using the perovskite film composed of small (∼100 nm) perovskite grains (D-0) exhibits complete loss of PCE after storage under the ambient atmosphere for only 15 days and a PCE loss of up to 70 % with storage in the glove box for 30 days. These results suggest that, even under H 2 O-free conditions, the chemical- and thermal-induced production of pin holes at the grain boundaries of the perovskite film could be the reason for long-term instability of inverted perovskite solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. One Adaptive Synchronization Approach for Fractional-Order Chaotic System with Fractional-Order 1 < q < 2

    Science.gov (United States)

    Zhou, Ping; Bai, Rongji

    2014-01-01

    Based on a new stability result of equilibrium point in nonlinear fractional-order systems for fractional-order lying in 1 < q < 2, one adaptive synchronization approach is established. The adaptive synchronization for the fractional-order Lorenz chaotic system with fractional-order 1 < q < 2 is considered. Numerical simulations show the validity and feasibility of the proposed scheme. PMID:25247207

  17. Imaging of first-order surface-related multiples by reverse-time migration

    Science.gov (United States)

    Liu, Xuejian; Liu, Yike; Hu, Hao; Li, Peng; Khan, Majid

    2017-02-01

    Surface-related multiples have been utilized in the reverse-time migration (RTM) procedures, and additional illumination for subsurface can be provided. Meanwhile, many cross-talks are generated from undesired interactions between forward- and backward-propagated seismic waves. In this paper, subsequent to analysing and categorizing these cross-talks, we propose RTM of first-order multiples to avoid most undesired interactions in RTM of all-order multiples, where only primaries are forward-propagated and crosscorrelated with the backward-propagated first-order multiples. With primaries and multiples separated during regular seismic data processing as the input data, first-order multiples can be obtained by a two-step scheme: (1) the dual-prediction of higher-order multiples; and (2) the adaptive subtraction of predicted higher-order multiples from all-order multiples within local offset-time windows. In numerical experiments, two synthetic and a marine field data sets are used, where different cross-talks generated by RTM of all-order multiples can be identified and the proposed RTM of first-order multiples can provide a very interpretable image with a few cross-talks.

  18. Soil moisture storage and hillslope stability

    Directory of Open Access Journals (Sweden)

    A. Talebi

    2007-09-01

    Full Text Available Recently, we presented a steady-state analytical hillslope stability model to study rain-induced shallow landslides. This model is based on kinematic wave dynamics of saturated subsurface storage and the infinite slope stability assumption. Here we apply the model to investigate the effect of neglecting the unsaturated storage on the assessment of slope stability in the steady-state hydrology. For that purpose we extend the hydrological model to compute the soil pore pressure distribution over the entire flow domain. We also apply this model for hillslopes with non-constant soil depth to compare the stability of different hillslopes and to find the critical slip surface in hillslopes with different geometric characteristics. In order to do this, we incorporate more complex approaches to compute slope stability (Janbu's non-circular method and Bishop's simplified method in the steady-state analytical hillslope stability model. We compare the safety factor (FS derived from the infinite slope stability method and the more complex approach for two cases: with and without the soil moisture profile in the unsaturated zone. We apply this extended hillslope stability model to nine characteristic hillslope types with three different profile curvatures (concave, straight, convex and three different plan shapes (convergent, parallel, divergent. Overall, we find that unsaturated zone storage does not play a critical role in determining the factor of safety for shallow and deep landslides. As a result, the effect of the unsaturated zone storage on slope stability can be neglected in the steady-state hydrology and one can assume the same bulk specific weight below and above the water table. We find that steep slopes with concave profile and convergent plan shape have the least stability. We also demonstrate that in hillslopes with non-constant soil depth (possible deep landslides, the ones with convex profiles and convergent plan shapes have

  19. Stability conditions and phase diagrams for two-component Fermi gases with population imbalance

    International Nuclear Information System (INIS)

    Chen Qijin; He Yan; Chien, C.-C.; Levin, K.

    2006-01-01

    Superfluidity in atomic Fermi gases with population imbalance has recently become an exciting research focus. There is considerable disagreement in the literature about the appropriate stability conditions for states in the phase diagram throughout the BCS to Bose-Einstein condensation crossover. Here we discuss these stability conditions for homogeneous polarized superfluid phases, and compare with recent alternative proposals. The requirement of a positive second-order partial derivative of the thermodynamic potential with respect to the fermionic excitation gap Δ (at fixed chemical potentials) is demonstrated to be equivalent to the positive definiteness of the particle number susceptibility matrix. In addition, we show the positivity of the effective pair mass constitutes another nontrivial stability condition. These conditions determine the (local) stability of the system towards phase separation (or other ordered phases). We also study systematically the effects of finite temperature and the related pseudogap on the phase diagrams defined by our stability conditions

  20. The second-order luminosity-redshift relation in a generic inhomogeneous cosmology

    International Nuclear Information System (INIS)

    Ben-Dayan, Ido; Marozzi, Giovanni; Veneziano, Gabriele; Nugier, Fabien

    2012-01-01

    After recalling a general non-perturbative expression for the luminosity-redshift relation holding in a recently proposed 'geodesic light-cone' gauge, we show how it can be transformed to phenomenologically more convenient gauges in which cosmological perturbation theory is better understood. We present, in particular, the complete result on the luminosity-redshift relation in the Poisson gauge up to second order for a fairly generic perturbed cosmology, assuming that appreciable vector and tensor perturbations are only generated at second order. This relation provides a basic ingredient for the computation of the effects of stochastic inhomogeneities on precision dark-energy cosmology whose results we have anticipated in a recent letter. More generally, it can be used in connection with any physical information carried by light-like signals traveling along our past light-cone

  1. One Adaptive Synchronization Approach for Fractional-Order Chaotic System with Fractional-Order 1

    Directory of Open Access Journals (Sweden)

    Ping Zhou

    2014-01-01

    Full Text Available Based on a new stability result of equilibrium point in nonlinear fractional-order systems for fractional-order lying in 1order Lorenz chaotic system with fractional-order 1

  2. A validated specific stability-indicating RP-HPLC assay method for Ambrisentan and its related substances.

    Science.gov (United States)

    Narayana, M B V; Chandrasekhar, K B; Rao, B M

    2014-09-01

    A validated specific stability-indicating reverse-phase liquid chromatographic method was developed for the quantitative determination of Ambrisentan as well as its related substances in bulk samples, pharmaceutical dosage forms in the presence of degradation products and its related impurities. Forced degradation studies were performed on bulk samples of Ambrisentan as per the ICH-prescribed stress conditions using acid, base, oxidative, thermal stress and photolytic degradation to show the stability-indicating power of the LC method. Significant degradation in acidic, basic stress conditions was observed and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from the forced degradation studies and the impurity-spiked solution. Good resolution between the peaks corresponds to Ambrisentan-related impurities and degradation products from the analyte were achieved on a SunFire C18 column using a mobile phase consisting of a mixture of potassium dihydrogen orthophosphate at a pH adjusted to 2.5 with ortho-phosphoric acid in water and a mixture of acetonitrile:methanol using a simple linear gradient. The detection was carried out at 225 nm. The limit of detection and the limit of quantification for the Ambrisentan and its related impurities were established. The stressed test solutions were assayed against the qualified working standard of Ambrisentan and the mass balance in each case was between 98.9 and 100.3%, indicating that the developed LC method was stability indicating. Validation of the developed LC method was carried out as per the ICH requirements. The developed method was found to be suitable to check the quality of bulk samples of Ambrisentan at the time of batch release and also during its storage (long-term and accelerated stability). © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Equilibrium and stability of a rotating plasma

    International Nuclear Information System (INIS)

    Janssen, P.A.E.M.

    1979-01-01

    The author considers the equilibrium and stability of a rotating plasma. The kinetic equations for ions and electrons supplemented with the Maxwell equations and the appropriate boundary conditions are used. Two different models for the rotating plasma are considered: the equilibrium of a 'fast' rotating plasma (Magneto Hydrodynamic ordering) and the stability of a slowly rotating, 'weakly' unstable plasma (Finite Larmor Radius ordering). A striking difference between these orderings is the fact that, regarding the stability of the plasma, for a F.L.R. plasma viscosity effects due to the finite Larmor radius are important, whereas in a M.H.D. plasma they are negligible (at least to the required order). (Auth.)

  4. Goal conflict and the moderating effects of intention stability in intention-behavior relations: physical activity among Hong Kong chinese.

    Science.gov (United States)

    Li, Kin-Kit; Chan, Darius K S

    2008-02-01

    This study examined how goal conflict influences the pattern of the moderating effects of intention stability on the intention-behavior relations in the context of physical activity participation. A longitudinal study of 136 young adult students with three waves of data collection (a 2-week interval between waves) was conducted. Results showed a significant three-way interaction among intention, goal conflict,& intention stability in explaining vigorous-intensity physical activity (Beta = -.25, p goal conflict was low, the intention-behavior relations were stronger with stable intentions and weaker with unstable intentions. However, when the level of goal conflict was high, the intention-behavior relations were weaker with stable intentions and stronger with unstable intentions. Possible underlying processes of goal conflict and intention stability on the intention-behavior relations are discussed.

  5. Analytical relation between the fifth-order vacuum-polarization coefficient b5 and the fifth-order Gell-Mann-Low function Ψ5

    International Nuclear Information System (INIS)

    Nigam, B.P.

    1994-01-01

    An expression for the fifth-order vacuum-polarization coefficient b 5 was reported. Recently, Broadhurst et al have indicated that this is in error by the omission of a fifth-order term. In this letter, after including the fifth-order Gell-Mann-Low (GML) function Ψ 5 in the GML equation, a relation between b 5 and Ψ 5 is derived. (author)

  6. Undecidability of the Logic of Overlap Relation over Discrete Linear Orderings

    DEFF Research Database (Denmark)

    Bresolin, Davide; Della Monica, Dario; Goranko, Valentin

    2010-01-01

    . Still, decidability is the rule for the fragments of HS with only one modal operator, based on an Allen’s relation. In this paper, we show that the logic O of the Overlap relation, when interpreted over discrete linear orderings, is an exception. The proof is based on a reduction from the undecidable...

  7. De Sitter and scaling solutions in a higher-order modified teleparallel theory

    Energy Technology Data Exchange (ETDEWEB)

    Paliathanasis, Andronikos, E-mail: anpaliat@phys.uoa.gr [Instituto de Ciencias Físicas y Matemáticas, Universidad Austral de Chile, Valdivia (Chile)

    2017-08-01

    The existence and the stability conditions for some exact relativistic solutions of special interest are studied in a higher-order modified teleparallel gravitational theory. The theory with the use of a Lagrange multiplier is equivalent with that of General Relativity with a minimally coupled noncanonical field. The conditions for the existence of de Sitter solutions and ideal gas solutions in the case of vacuum are studied as also the stability criteria. Furthermore, in the presence of matter the behaviour of scaling solutions is given. Finally, we discuss the degrees of freedom of the field equations and we reduce the field equations in an algebraic equation, where in order to demonstrate our result we show how this noncanonical scalar field can reproduce the Hubble function of Λ-cosmology.

  8. Solid-State Characterization and Relative Formation Enthalpies To Evaluate Stability of Cocrystals of an Antidiabetic Drug.

    Science.gov (United States)

    Duggirala, Naga Kiran; Frericks Schmidt, Heather L; Lei, Zhaohui; Zaworotko, Michael J; Krzyzaniak, Joseph F; Arora, Kapildev K

    2018-05-07

    The current study integrates formation enthalpy and traditional slurry experiments to quickly assess the physical stability of cocrystal drug substance candidates for their potential to support drug development. Cocrystals of an antidiabetic drug (GKA) with nicotinamide (NMA), vanillic acid (VLA), and ethyl vanillin (EVL) were prepared and characterized by powder X-ray diffractometry (PXRD), spectroscopic, and thermal techniques. The formation enthalpies of the cocrystals, and their physical mixtures (GKA + coformer) were measured by the differential scanning calorimetry (DSC) method reported by Zhang et al. [ Cryst. Growth Des. 2012 , 12 ( 8 ), 4090 - 4097 ]. The experimentally measured differences in the relative formation enthalpies obtained by integrating the heat flow of each cocrystal against the respective physical mixture were correlated to the physical stability of the cocrystals in the solid state. The relative formation enthalpies of all of the cocrystals studied suggest that the cocrystals are not physically stable at room temperature versus their physical mixtures. To further address relative stability, the cocrystals were slurried in 30% v/v aqueous ethanol, and it was observed that all of the cocrystals revert to GKA within 48 h at room temperature. The slurry experiments are consistent with the relative instability of the cocrystals with respect to their physical mixtures suggested by the DSC results.

  9. Energy Management System Based on Fuzzy fractional order PID Controller for Transient Stability Improvement in Microgrids with Energy Storage

    DEFF Research Database (Denmark)

    Moafi, Milad; Marzband, Mousa; Savaghebi, Mehdi

    2016-01-01

    in the islanded Microgrid (MG). To increase performance for a wide range of power system operating conditions, an energy management systems (EMS) is proposed based on a fuzzy fractional order PID (FFOPID) controller. It is able to analyze and simulate the dynamic behavior in grid connected MGs. This controller...... is proposed in the MG encompassing distributed generation resources with “plug and play” ability. The performance of FFOPID controller is verified for frequency control purposes and to support internal bus voltage in both islanded and grid connected operating modes in accordance with the failure time. Energy...... combined with a PID-controller (termed as FLPID) and Fuzzy fractional order PID (termed as FFOPID) are implemented according to the characteristics and limitations of overloading and state of charge (SOC). The obtained results show good performance of FFOPID controllers by improving the transient stability...

  10. An accurate and efficient reliability-based design optimization using the second order reliability method and improved stability transformation method

    Science.gov (United States)

    Meng, Zeng; Yang, Dixiong; Zhou, Huanlin; Yu, Bo

    2018-05-01

    The first order reliability method has been extensively adopted for reliability-based design optimization (RBDO), but it shows inaccuracy in calculating the failure probability with highly nonlinear performance functions. Thus, the second order reliability method is required to evaluate the reliability accurately. However, its application for RBDO is quite challenge owing to the expensive computational cost incurred by the repeated reliability evaluation and Hessian calculation of probabilistic constraints. In this article, a new improved stability transformation method is proposed to search the most probable point efficiently, and the Hessian matrix is calculated by the symmetric rank-one update. The computational capability of the proposed method is illustrated and compared to the existing RBDO approaches through three mathematical and two engineering examples. The comparison results indicate that the proposed method is very efficient and accurate, providing an alternative tool for RBDO of engineering structures.

  11. Stabilization of carbon in composts and biochars in relation to carbon sequestration and soil fertility

    Energy Technology Data Exchange (ETDEWEB)

    Bolan, N.S., E-mail: Nanthi.Bolan@unisa.edu.au [Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, SA 5095 (Australia); Cooperative Research Centre for Contaminants Assessment and Remediation of the Environment (CRC CARE), University of South Australia, SA 5095 (Australia); Kunhikrishnan, A. [Chemical Safety Division, Department of Agro-Food Safety, National Academy of Agricultural Science, Suwon-si, Gyeonggi-do 441-707 (Korea, Republic of); Choppala, G.K.; Thangarajan, R. [Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, SA 5095 (Australia); Cooperative Research Centre for Contaminants Assessment and Remediation of the Environment (CRC CARE), University of South Australia, SA 5095 (Australia); Chung, J.W. [Department of Environmental Engineering, Gyeongnam National University of Science and Technology, Dongjin-ro 33, Jinju, Gyeongnam, 660-758 (Korea, Republic of)

    2012-05-01

    There have been increasing interests in the conversion of organic residues into biochars in order to reduce the rate of decomposition, thereby enhancing carbon (C) sequestration in soils. However energy is required to initiate the pyrolysis process during biochar production which can also lead to the release of greenhouse gasses. Alternative methods can be used to stabilize C in composts and other organic residues without impacting their quality. The objectives of this study include: (i) to compare the rate of decomposition among various organic amendments and (ii) to examine the effect of clay materials on the stabilization of C in organic amendments. The decomposition of a number of organic amendments (composts and biochars) was examined by monitoring the release of carbon-dioxide using respiration experiments. The results indicated that the rate of decomposition as measured by half life (t{sub 1/2}) varied between the organic amendments and was higher in sandy soil than in clay soil. The half life value ranged from 139 days in the sandy soil and 187 days in the clay soil for poultry manure compost to 9989 days for green waste biochar. Addition of clay materials to compost decreased the rate of decomposition, thereby increasing the stabilization of C. The half life value for poultry manure compost increased from 139 days to 620, 806 and 474 days with the addition of goethite, gibbsite and allophane, respectively. The increase in the stabilization of C with the addition of clay materials may be attributed to the immobilization of C, thereby preventing it from microbial decomposition. Stabilization of C in compost using clay materials did not impact negatively the value of composts in improving soil quality as measured by potentially mineralizable nitrogen and microbial biomass carbon in soil. - Graphical abstract: Stabilization of compost using clay materials (e.g. allophane) enhances carbon sequestration in soils. Highlights: Black

  12. Stabilization of carbon in composts and biochars in relation to carbon sequestration and soil fertility

    International Nuclear Information System (INIS)

    Bolan, N.S.; Kunhikrishnan, A.; Choppala, G.K.; Thangarajan, R.; Chung, J.W.

    2012-01-01

    There have been increasing interests in the conversion of organic residues into biochars in order to reduce the rate of decomposition, thereby enhancing carbon (C) sequestration in soils. However energy is required to initiate the pyrolysis process during biochar production which can also lead to the release of greenhouse gasses. Alternative methods can be used to stabilize C in composts and other organic residues without impacting their quality. The objectives of this study include: (i) to compare the rate of decomposition among various organic amendments and (ii) to examine the effect of clay materials on the stabilization of C in organic amendments. The decomposition of a number of organic amendments (composts and biochars) was examined by monitoring the release of carbon-dioxide using respiration experiments. The results indicated that the rate of decomposition as measured by half life (t 1/2 ) varied between the organic amendments and was higher in sandy soil than in clay soil. The half life value ranged from 139 days in the sandy soil and 187 days in the clay soil for poultry manure compost to 9989 days for green waste biochar. Addition of clay materials to compost decreased the rate of decomposition, thereby increasing the stabilization of C. The half life value for poultry manure compost increased from 139 days to 620, 806 and 474 days with the addition of goethite, gibbsite and allophane, respectively. The increase in the stabilization of C with the addition of clay materials may be attributed to the immobilization of C, thereby preventing it from microbial decomposition. Stabilization of C in compost using clay materials did not impact negatively the value of composts in improving soil quality as measured by potentially mineralizable nitrogen and microbial biomass carbon in soil. - Graphical abstract: Stabilization of compost using clay materials (e.g. allophane) enhances carbon sequestration in soils. Highlights: ► Comparison of decomposition rate

  13. A simplified spatial model for BWR stability

    International Nuclear Information System (INIS)

    Berman, Y.; Lederer, Y.; Meron, E.

    2012-01-01

    A spatial reduced order model for the study of BWR stability, based on the phenomenological model of March-Leuba et al., is presented. As one dimensional spatial dependence of the neutron flux, fuel temperature and void fraction is introduced, it is possible to describe both global and regional oscillations of the reactor power. Both linear stability analysis and numerical analysis were applied in order to describe the parameters which govern the model stability. The results were found qualitatively similar to past results. Doppler reactivity feedback was found essential for the explanation of the different regions of the flow-power stability map. (authors)

  14. Hall magnetohydrodynamics: Conservation laws and Lyapunov stability

    International Nuclear Information System (INIS)

    Holm, D.D.

    1987-01-01

    Hall electric fields produce circulating mass flow in confined ideal-fluid plasmas. The conservation laws, Hamiltonian structure, equilibrium state relations, and Lyapunov stability conditions are presented here for ideal Hall magnetohydrodynamics (HMHD) in two and three dimensions. The approach here is to use the remarkable array of nonlinear conservation laws for HMHD that follow from its Hamiltonian structure in order to construct explicit Lyapunov functionals for the HMHD equilibrium states. In this way, the Lyapunov stability analysis provides classes of HMHD equilibria that are stable and whose linearized initial-value problems are well posed (in the sense of possessing continuous dependence on initial conditions). Several examples are discussed in both two and three dimensions

  15. M-Theory Model-Building and Proton Stability

    CERN Document Server

    Ellis, Jonathan Richard; Nanopoulos, Dimitri V; Ellis, John; Faraggi, Alon E.

    1998-01-01

    We study the problem of baryon stability in M theory, starting from realistic four-dimensional string models constructed using the free-fermion formulation of the weakly-coupled heterotic string. Suitable variants of these models manifest an enhanced custodial gauge symmetry that forbids to all orders the appearance of dangerous dimension-five baryon-decay operators. We exhibit the underlying geometric (bosonic) interpretation of these models, which have a $Z_2 \\times Z_2$ orbifold structure similar, but not identical, to the class of Calabi-Yau threefold compactifications of M and F theory investigated by Voisin and Borcea. A related generalization of their work may provide a solution to the problem of proton stability in M theory.

  16. M-theory model-building and proton stability

    International Nuclear Information System (INIS)

    Ellis, J.; Faraggi, A.E.; Nanopoulos, D.V.; Houston Advanced Research Center, The Woodlands, TX; Academy of Athens

    1997-09-01

    The authors study the problem of baryon stability in M theory, starting from realistic four-dimensional string models constructed using the free-fermion formulation of the weakly-coupled heterotic string. Suitable variants of these models manifest an enhanced custodial gauge symmetry that forbids to all orders the appearance of dangerous dimension-five baryon-decay operators. The authors exhibit the underlying geometric (bosonic) interpretation of these models, which have a Z 2 x Z 2 orbifold structure similar, but not identical, to the class of Calabi-Yau threefold compactifications of M and F theory investigated by Voisin and Borcea. A related generalization of their work may provide a solution to the problem of proton stability in M theory

  17. Immunogenicity of biopharmaceuticals and biosimilars in relation to storage, handling and stability

    International Nuclear Information System (INIS)

    Hincal, F.

    2009-01-01

    Therapeutic proteins or biopharmaceuticals provide effective treatment for many diseases and medical conditions, and vaccines, immunoglobulins and monoclonal antibodies are critical biodefense biopharmaceuticals which constitute an indispensable part of biodefense stockpiles. The manufacturing process for biopharmaceuticals and their generic forms which are called biosimilars is far more complex than for low molecular weight drugs and generics. Any minor change made at any stage may have a critical effect on the clinical efficacy and safety. Potential immunogenicity is the key issue for biopharmaceuticals and biosimilars and may have serious clinical consequences ranging from allergy and anaphylaxis, as well as loss of efficacy of the product. Immunogenicity may be influenced by factors related to manufacturing process, formulation, aggregate formation, contaminants and impurities, and also by the factors related to the storage and handling. Stability is particularly important with larger protein molecules, because their in vivo effects often depend on their three-dimensional structure. Proteins usually aggregate from partially unfolded molecules and aggregates can enhance immunogenicity. Although product formulations are developed to maximize and maintain the fraction of the protein molecules present in the native state, significant amounts of aggregates can form, especially over pharmaceutically relevant time scales and under stress conditions. Exposure to air-liquid and solid-liquid interfaces, light, temperature fluctuations or minor impurities can induce aggregation. Such exposure can occur during processing steps, as well as in the final product container during storage, shipment and handling. Biopharmaceuticals are particularly sensitive to temperature changes and/or shaking. Strict storage and handling conditions and timely and effective stability/shelf-life testing are therefore essential for maintaining product integrity and stability, and hence efficacy

  18. Dynamic behaviours and control of fractional-order memristor-based ...

    Indian Academy of Sciences (India)

    Dynamics of fractional-order memristor circuit system and its control are investigated in this paper. With the help of stability theory of fractional-order systems, stability of its equilibrium points is analysed. Then, the chaotic behaviours are validated using phase portraits, the Lyapunov exponents and bifurcation diagrams with ...

  19. A study on stability of rotating magnets

    International Nuclear Information System (INIS)

    Higuchi, N.; Kaiho, K.; Ishii, I.

    1996-01-01

    Superconducting power generators are being developed in Japan, as a part of a R and D program on energy technology, the New Sunshine Project. In this development, national laboratories are taking a role of fundamental studies to contribute to the R and D being carried out mainly by the manufacturers involved in a research association, Super-GM. Stabilities of magnets in a high gravitational field up to 2,000 G are discussed, based upon the experimental results of forced quench tests in a set of rotating magnets, in order to establish the stability design criterion of field windings of superconducting generators. Relations of propagation velocities, recovery currents, minimum quench energy and heat transfer characteristics are studied, a good agreement between the experimental results and a theory confirmed the improvement of magnet stability in a high gravitational field because of the enhanced heat transfer characteristics

  20. Distinct Short-Range Order Is Inherent to Small Amorphous Calcium Carbonate Clusters (<2 nm)

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Shengtong [Physical Chemistry, University of Konstanz, Universitätsstrasse 10 78457 Konstanz Germany; School of Chemical Engineering, State Key Laboratory of Chemical Engineering, Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road Shanghai 200237 P.R. China; Chevrier, Daniel M. [Department of Chemistry and Institute for Research in Materials, Dalhousie University, Halifax Nova Scotia B3H 4R2 Canada; Zhang, Peng [Department of Chemistry and Institute for Research in Materials, Dalhousie University, Halifax Nova Scotia B3H 4R2 Canada; Gebauer, Denis [Physical Chemistry, University of Konstanz, Universitätsstrasse 10 78457 Konstanz Germany; Cölfen, Helmut [Physical Chemistry, University of Konstanz, Universitätsstrasse 10 78457 Konstanz Germany

    2016-09-09

    Amorphous intermediate phases are vital precursors in the crystallization of many biogenic minerals. While inherent short-range orders have been found in amorphous calcium carbonates (ACCs) relating to different crystalline forms, it has never been clarified experimentally whether such orders already exist in very small clusters less than 2 nm in size. Here, we studied the stability and structure of 10,12-pentacosadiynoic acid (PCDA) protected ACC clusters with a core size of ca. 1.4 nm consisting of only seven CaCO3 units. Ligand concentration and structure are shown to be key factors in stabilizing the ACC clusters. More importantly, even in such small CaCO3 entities, a proto-calcite short-range order can be identified but with a relatively high degree of disorder that arises from the very small size of the CaCO3 core. Our findings support the notion of a structural link between prenucleation clusters, amorphous intermediates, and final crystalline polymorphs, which appears central to the understanding of polymorph selection.

  1. Checking the transverse Ward-Takahashi relation at one-loop order in four dimensions

    International Nuclear Information System (INIS)

    Pennington, M R; Williams, R

    2006-01-01

    Some time ago Takahashi derived the so-called transverse relations relating Green's functions of different orders to complement the well-known Ward-Green-Takahashi identities of gauge theories by considering wedge rather than inner products. These transverse relations have the potential to determine the full fermion-boson vertex in terms of the renormalization functions of the fermion propagator. He and Yu have given an indicative proof at one-loop level in four dimensions. However, their construct involves the fourth-rank Levi-Civita tensor defined only unambiguously in four dimensions exactly where the loop integrals diverge. Consequently, here we explicitly check the proposed transverse Ward-Takahashi relation holds at one-loop order in d-dimensions, with d = 4 + ε

  2. Strong Stability Preserving Two-step Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.; Gottlieb, Sigal; Macdonald, Colin B.

    2011-01-01

    We investigate the strong stability preserving (SSP) property of two-step Runge–Kutta (TSRK) methods. We prove that all SSP TSRK methods belong to a particularly simple subclass of TSRK methods, in which stages from the previous step are not used. We derive simple order conditions for this subclass. Whereas explicit SSP Runge–Kutta methods have order at most four, we prove that explicit SSP TSRK methods have order at most eight. We present explicit TSRK methods of up to eighth order that were found by numerical search. These methods have larger SSP coefficients than any known methods of the same order of accuracy and may be implemented in a form with relatively modest storage requirements. The usefulness of the TSRK methods is demonstrated through numerical examples, including integration of very high order weighted essentially non-oscillatory discretizations.

  3. Strong Stability Preserving Two-step Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.

    2011-12-22

    We investigate the strong stability preserving (SSP) property of two-step Runge–Kutta (TSRK) methods. We prove that all SSP TSRK methods belong to a particularly simple subclass of TSRK methods, in which stages from the previous step are not used. We derive simple order conditions for this subclass. Whereas explicit SSP Runge–Kutta methods have order at most four, we prove that explicit SSP TSRK methods have order at most eight. We present explicit TSRK methods of up to eighth order that were found by numerical search. These methods have larger SSP coefficients than any known methods of the same order of accuracy and may be implemented in a form with relatively modest storage requirements. The usefulness of the TSRK methods is demonstrated through numerical examples, including integration of very high order weighted essentially non-oscillatory discretizations.

  4. The stability of some asteroids

    International Nuclear Information System (INIS)

    Vicente, R.O.

    1983-01-01

    The utilization of two different stability criteria, namely, Hill's modified stability criterium and the method of surface of section, has been employed for asteroid orbits. The idea is to compute different criteria of stability for the same asteroids in order to compare the results and see the practical interest of the computations for researches about evolutionary trends of individual asteroids, groups and families of asteroids. (Auth.)

  5. Higher-order techniques for some problems of nonlinear control

    Directory of Open Access Journals (Sweden)

    Sarychev Andrey V.

    2002-01-01

    Full Text Available A natural first step when dealing with a nonlinear problem is an application of some version of linearization principle. This includes the well known linearization principles for controllability, observability and stability and also first-order optimality conditions such as Lagrange multipliers rule or Pontryagin's maximum principle. In many interesting and important problems of nonlinear control the linearization principle fails to provide a solution. In the present paper we provide some examples of how higher-order methods of differential geometric control theory can be used for the study nonlinear control systems in such cases. The presentation includes: nonlinear systems with impulsive and distribution-like inputs; second-order optimality conditions for bang–bang extremals of optimal control problems; methods of high-order averaging for studying stability and stabilization of time-variant control systems.

  6. On the stability of Einstein static universe in doubly general relativity scenario

    Energy Technology Data Exchange (ETDEWEB)

    Khodadi, M.; Nozari, K. [University of Mazandaran, Department of Physics, Faculty of Basic Sciences, Babolsar (Iran, Islamic Republic of); Heydarzade, Y. [Azarbaijan Shahid Madani University, Department of Physics, Tabriz (Iran, Islamic Republic of); Darabi, F. [Azarbaijan Shahid Madani University, Department of Physics, Tabriz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of)

    2015-12-15

    By presenting a relation between the average energy of the ensemble of probe photons and the energy density of the universe, in the context of gravity's rainbow or the doubly general relativity scenario, we introduce a rainbow FRW universe model. By analyzing the fixed points in the flat FRW model modified by two well-known rainbow functions, we find that the finite time singularity avoidance (i.e. Big Bang) may still remain as a problem. Then we follow the ''emergent universe'' scenario in which there is no beginning of time and consequently there is no Big-Bang singularity. Moreover, we study the impact of high energy quantum gravity modifications related to the gravity's rainbow on the stability conditions of an ''Einstein static universe'' (ESU). We find that independent of the particular rainbow function, the positive energy condition dictates a positive spatial curvature for the universe. In fact, without raising a nonphysical energy condition in the quantum gravity regimes, we can observe agreement between gravity's rainbow scenario and the basic assumption of the modern version of the ''emergent universe''. We show that in the absence and presence of an energy-dependent cosmological constant Λ(ε), a stable Einstein static solution is available versus the homogeneous and linear scalar perturbations under the variety of the obtained conditions. Also, we explore the stability of ESU against the vector and tensor perturbations. (orig.)

  7. On the stability of Einstein static universe in doubly general relativity scenario

    Energy Technology Data Exchange (ETDEWEB)

    Khodadi, M., E-mail: m.khodadi@stu.umz.ac.ir [Department of Physics, Faculty of Basic Sciences, University of Mazandaran, P. O. Box 47416-95447, Babolsar (Iran, Islamic Republic of); Heydarzade, Y., E-mail: heydarzade@azaruniv.edu [Department of Physics, Azarbaijan Shahid Madani University, 53714-161, Tabriz (Iran, Islamic Republic of); Nozari, K., E-mail: knozari@umz.ac.ir [Department of Physics, Faculty of Basic Sciences, University of Mazandaran, P. O. Box 47416-95447, Babolsar (Iran, Islamic Republic of); Darabi, F., E-mail: f.darabi@azaruniv.edu [Department of Physics, Azarbaijan Shahid Madani University, 53714-161, Tabriz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), 55134-441, Maragha (Iran, Islamic Republic of)

    2015-12-12

    By presenting a relation between the average energy of the ensemble of probe photons and the energy density of the universe, in the context of gravity’s rainbow or the doubly general relativity scenario, we introduce a rainbow FRW universe model. By analyzing the fixed points in the flat FRW model modified by two well-known rainbow functions, we find that the finite time singularity avoidance (i.e. Big Bang) may still remain as a problem. Then we follow the “emergent universe” scenario in which there is no beginning of time and consequently there is no Big-Bang singularity. Moreover, we study the impact of high energy quantum gravity modifications related to the gravity’s rainbow on the stability conditions of an “Einstein static universe” (ESU). We find that independent of the particular rainbow function, the positive energy condition dictates a positive spatial curvature for the universe. In fact, without raising a nonphysical energy condition in the quantum gravity regimes, we can observe agreement between gravity’s rainbow scenario and the basic assumption of the modern version of the “emergent universe”. We show that in the absence and presence of an energy-dependent cosmological constant Λ(ϵ), a stable Einstein static solution is available versus the homogeneous and linear scalar perturbations under the variety of the obtained conditions. Also, we explore the stability of ESU against the vector and tensor perturbations.

  8. Defect ordering in aliovalently doped cubic zirconia from first principles

    International Nuclear Information System (INIS)

    Bogicevic, A.; Wolverton, C.; Crosbie, G.M.; Stechel, E.B.

    2001-01-01

    Defect ordering in aliovalently doped cubic-stabilized zirconia is studied using gradient corrected density-functional calculations. Intra- and intersublattice ordering interactions are investigated for both cation (Zr and dopant ions) and anion (oxygen ions and vacancies) species. For yttria-stabilized zirconia, the crystal structure of the experimentally identified, ordered compound δ-Zr 3 Y 4 O 12 is established, and we predict metastable zirconia-rich ordered phases. Anion vacancies repel each other at short separations, but show an energetic tendency to align as third-nearest neighbors along directions. Calculations with divalent (Be, Mg, Ca, Sr, Ba) and trivalent (Y, Sc, B, Al, Ga, In) oxides show that anion vacancies prefer to be close to the smaller of the cations (Zr or dopant ion). When the dopant cation is close in size to Zr, the vacancies show no particular preference, and are thus less prone to be bound preferentially to any particular cation type when the vacancies traverse such oxides. This ordering tendency offers insight into the observed high conductivity of Y 2 O 3 - and Sc 2 O 3 -stabilized zirconia, as well as recent results using, e.g., lanthanide oxides. The calculations point to In 2 O 3 as a particularly promising stabilizer for high ionic conductivity. Thus we are able to directly link (thermodynamic) defect ordering to (kinetic) ionic conductivity in cubic-stabilized zirconia using first-principles atomistic calculations

  9. Rubber effect and stabilization of martensites in noble metal based alloys

    International Nuclear Information System (INIS)

    Marukawa, K.; Takezawa, K.; Hoshi, H.

    1999-01-01

    In a previous paper, it has been pointed out that the rubber effect and stabilization of the martensite phase are caused by short range reordering during aging [K. Marukawa, K. Tsuchiya, Scripta Metall. Mater. 32 (1995) 77]. This view was further examined by experimental and theoretical studies. It has been found that the change in electrical resistivity produced by aging is well correlated with magnitudes of these effects. The relation between the short range order parameters and the representative quantities of these effects was formulated on the basis of thermodynamics. Quantitative evaluation was performed by numerical calculations utilizing the Monte Carlo method. It was found that the rubber effect is prominent when the aging temperature is in the vicinity of the order-disorder transition temperature. It was also shown that in most cases disordering or lowering in the long range order causes the stabilization. (orig.)

  10. Open Problems Related to the Hurwitz Stability of Polynomials Segments

    Directory of Open Access Journals (Sweden)

    Baltazar Aguirre-Hernández

    2018-01-01

    Full Text Available In the framework of robust stability analysis of linear systems, the development of techniques and methods that help to obtain necessary and sufficient conditions to determine stability of convex combinations of polynomials is paramount. In this paper, knowing that Hurwitz polynomials set is not a convex set, a brief overview of some results and open problems concerning the stability of the convex combinations of Hurwitz polynomials is then provided.

  11. On local attraction properties and a stability index for heteroclinic connections

    International Nuclear Information System (INIS)

    Podvigina, Olga; Ashwin, Peter

    2011-01-01

    Some invariant sets may attract a nearby set of initial conditions but nonetheless repel a complementary nearby set of initial conditions. For a given invariant set X ⊂ R n with a basin of attraction N, we define a stability index σ(x) of a point x in X that characterizes the local extent of the basin. Let B ε denote a ball of radius ε about x. If σ(x) > 0, then the measure of B ε setmn N relative the measure of the ball is O(ε |σ(x)| ), while if σ(x) ε intersection N relative the measure of the ball is of this order. We show that this index is constant along trajectories, and we relate this orbit invariant to other notions of stability such as Milnor attraction, essential asymptotic stability and asymptotic stability relative to a positive measure set. We adapt the definition to local basins of attraction (i.e. where N is defined as the set of initial conditions that are in the basin and whose trajectories remain local to X). This stability index is particularly useful for discussing the stability of robust heteroclinic cycles, where several authors have studied the appearance of cusps of instability near cycles that are Milnor attractors. We study simple (robust heteroclinic) cycles in R 4 and show that the local stability indices (and hence local stability properties) can be calculated in terms of the eigenvalues of the linearization of the vector field at steady states on the cycle. In doing this, we extend previous results of Krupa and Melbourne (1995 Ergod. Theory Dyn. Syst. 15 121–48; 2004 Proc. R. Soc. Edinb. A 134 1177–97) and give criteria for simple heteroclinic cycles in R 4 to be Milnor attractors

  12. Stabilization of carbon in composts and biochars in relation to carbon sequestration and soil fertility.

    Science.gov (United States)

    Bolan, N S; Kunhikrishnan, A; Choppala, G K; Thangarajan, R; Chung, J W

    2012-05-01

    There have been increasing interests in the conversion of organic residues into biochars in order to reduce the rate of decomposition, thereby enhancing carbon (C) sequestration in soils. However energy is required to initiate the pyrolysis process during biochar production which can also lead to the release of greenhouse gasses. Alternative methods can be used to stabilize C in composts and other organic residues without impacting their quality. The objectives of this study include: (i) to compare the rate of decomposition among various organic amendments and (ii) to examine the effect of clay materials on the stabilization of C in organic amendments. The decomposition of a number of organic amendments (composts and biochars) was examined by monitoring the release of carbon-dioxide using respiration experiments. The results indicated that the rate of decomposition as measured by half life (t(1/2)) varied between the organic amendments and was higher in sandy soil than in clay soil. The half life value ranged from 139 days in the sandy soil and 187 days in the clay soil for poultry manure compost to 9989 days for green waste biochar. Addition of clay materials to compost decreased the rate of decomposition, thereby increasing the stabilization of C. The half life value for poultry manure compost increased from 139 days to 620, 806 and 474 days with the addition of goethite, gibbsite and allophane, respectively. The increase in the stabilization of C with the addition of clay materials may be attributed to the immobilization of C, thereby preventing it from microbial decomposition. Stabilization of C in compost using clay materials did not impact negatively the value of composts in improving soil quality as measured by potentially mineralizable nitrogen and microbial biomass carbon in soil. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Finite Larmor radius effects on the stability properties of internal modes of a z-pinch

    International Nuclear Information System (INIS)

    Aakerstedt, H.O.

    1987-01-01

    From the Vlasov-fluid model a set of approximate stability equations describing the stability of a cylindrically symmetric z-pinch is derived. The equations are derived in the limit of small gyroradius and include first order kinetic effects such as finite ion Larmor radius effects and resonant ion effects. Neglecting the resonant ion terms, we explicitly solve this set of equations for a constant current density profile leading to a dispersion relation. FLR effects are shown for the case of m=1 internal mode to be stabilizing and for large wavenumbers k, using a trial function approach, absolute stabilization is found. (author)

  14. High-Order Frequency-Locked Loops

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    In very recent years, some attempts for designing high-order frequency-locked loops (FLLs) have been made. Nevertheless, the advantages and disadvantages of these structures, particularly in comparison with a standard FLL and high-order phase-locked loops (PLLs), are rather unclear. This lack...... study, and its small-signal modeling, stability analysis, and parameter tuning are presented. Finally, to gain insight about advantages and disadvantages of high-order FLLs, a theoretical and experimental performance comparison between the designed second-order FLL and a standard FLL (first-order FLL...

  15. Artificial in-plane ordering of textured YBa2Cu3O(7-x) films deposited on polycrystalline yttria-stabilized zirconia substrates

    Science.gov (United States)

    Harshavardhan, K. S.; Rajeswari, M.; Hwang, D. M.; Chen, C. Y.; Sands, T. D.; Venkatesan, T.; Tkaczyk, J. E.; Lay, K. W.; Safari, A.; Johnson, L.

    1992-12-01

    Anisotropic surface texturing of the polycrystalline yttria-stabilized zirconia substrates, prior to YBa2Cu3O(7-x) film deposition, is shown to promote in-plane (basal plane) ordering of the film growth in addition to the c-axis texturing. The Jc's of the films in the weak-link-dominated low-field regime are enhanced considerably, and this result is attributed to the reduction of weak links resulting from a reduction in the number of in-plane large-angle grain boundaries.

  16. Stability analysis of fractional-order generalized chaotic susceptible ...

    Indian Academy of Sciences (India)

    susceptible–infected–recovered epidemic model and its ... engineering and biology have already been studied by a number of ... In contrast to integer-order ... sures the inhibitory effect, β is the transmission or contact rate, γ is the rate of ...

  17. Wear and related evaluations of partially stabilized ZrO2

    International Nuclear Information System (INIS)

    Rice, R.W.; Wu, C.C.

    1985-01-01

    Pin-On-Disk (POD) tests show partially stabilized ZrO 2 (PSZ) crystals to have about the same wear as fully stabilized ZrO 2 crystals unit stabilizer contents are low enough (e.g., 4-5 wt % Y 2 O 3 ) so that some monoclinc ZrO 2 is present. Then wear increases substantially as stabilizer content is further reduced, and monoclinic content increases. Tests of PSZ-crystal cutting tools have not proved particularly successful, and rolling-contact fatigue tests of various PSZ materials showed them to be poor candidates for rolling-element bearings, with the later results indicating a petch-type dependence. Possible reasons for such limited or poor performance of PSZ, despite its good toughness, are discussed. Poor performance with concentrated loads is noted in particular, indicating limitations due to plastic flow

  18. The application of the Accelerated Stability Assessment Program (ASAP) to quality by design (QbD) for drug product stability.

    Science.gov (United States)

    Waterman, Kenneth Craig

    2011-09-01

    An isoconversion paradigm, where times in different temperature and humidity-controlled stability chambers are set to provide a fixed degradant level, is shown to compensate for the complex, non-single order kinetics of solid drug products. A humidity-corrected Arrhenius equation provides reliable estimates for temperature and relative humidity effects on degradation rates. A statistical protocol is employed to determine best fits for chemical stability data, which in turn allows for accurate estimations of shelf life (with appropriate confidence intervals) at any storage condition including inside packaging (based on the moisture vapor transmission rate of the packaging and moisture sorption isotherms of the internal components). These methodologies provide both faster results and far better predictions of chemical stability limited shelf life (expiry) than previously possible. Precise shelf-life estimations are generally determined using a 2-week, product-specific protocol. Once the model for a product is developed, it can play a critical role in providing the product understanding necessary for a quality by design (QbD) filing for product approval and enable rational control strategies to assure product stability. Moreover, this Accelerated Stability Assessment Program (ASAP) enables the coupling of product attributes (e.g., moisture content, packaging options) to allow for flexibility in how control strategies are implemented to provide a balance of cost, speed, and other factors while maintaining adequate stability.

  19. Understanding chemical-potential-related transient pore-pressure response to improve real-time borehole (in)stability predictions

    Energy Technology Data Exchange (ETDEWEB)

    Tare, U. A.; Mody, F. K.; Mese, A. I. [Haliburton Energy Services, TX (United States)

    2002-07-01

    In order to develop a real-time wellbore (in)stability modelling capability, experimental work was carried out to investigate the role of the chemical potential of drilling fluids on transient pore pressure and time-dependent rock property alterations of shale formations. Time-dependent alterations in the pore pressure, acoustic and rock properties of formations subjected to compressive tri-axial test were recorded during the experiments involving the Pore Pressure Transmission (PPT) test. Based on the transient pore pressure of shale exposed to the test fluid presented here, the 20 per cent calcium chloride showed a very low membrane efficiency of 4.45 per cent. The need for a thorough understanding of the drilling fluid/shale interaction prior to applying any chemical potential wellbore (in)stability model to real-time drilling operations was emphasized. 9 refs., 5 figs.

  20. The energetics of ordered intermetallic alloys (of the transition metals)

    International Nuclear Information System (INIS)

    Watson, R.E.; Weinert, M.; Davenport, J.W.; Fernando, G.W.; Bennett, L.H.

    1992-01-01

    The atomically ordered phases in ordered transition metal alloys are discussed. This chapter is divided into: physical parameters controlling phase stability (Hume-Rothery, structural maps, Miedema Hamiltonian), wave functions ampersand band theory, comment on entropy terms, cohesive energies (electron promotion energies, Hund's rule on orbital effects), structural energies/stabilities of elemental solids, total energies and atomic positions, charge transfer (Au alloys, charge tailing), heats of formation of ordered compounds

  1. Multiscale stabilization for convection-dominated diffusion in heterogeneous media

    KAUST Repository

    Calo, Victor M.

    2016-02-23

    We develop a Petrov-Galerkin stabilization method for multiscale convection-diffusion transport systems. Existing stabilization techniques add a limited number of degrees of freedom in the form of bubble functions or a modified diffusion, which may not be sufficient to stabilize multiscale systems. We seek a local reduced-order model for this kind of multiscale transport problems and thus, develop a systematic approach for finding reduced-order approximations of the solution. We start from a Petrov-Galerkin framework using optimal weighting functions. We introduce an auxiliary variable to a mixed formulation of the problem. The auxiliary variable stands for the optimal weighting function. The problem reduces to finding a test space (a dimensionally reduced space for this auxiliary variable), which guarantees that the error in the primal variable (representing the solution) is close to the projection error of the full solution on the dimensionally reduced space that approximates the solution. To find the test space, we reformulate some recent mixed Generalized Multiscale Finite Element Methods. We introduce snapshots and local spectral problems that appropriately define local weight and trial spaces. In particular, we use energy minimizing snapshots and local spectral decompositions in the natural norm associated with the auxiliary variable. The resulting spectral decomposition adaptively identifies and builds the optimal multiscale space to stabilize the system. We discuss the stability and its relation to the approximation property of the test space. We design online basis functions, which accelerate convergence in the test space, and consequently, improve stability. We present several numerical examples and show that one needs a few test functions to achieve an error similar to the projection error in the primal variable irrespective of the Peclet number.

  2. Self-esteem stability in relation to narcissism and psychological well-being

    Directory of Open Access Journals (Sweden)

    Saša Zorjan

    2013-06-01

    Full Text Available The concept of self-esteem stability has an important role in the understanding of interpersonal and psychological functioning of individuals. The purpose of this study was to examine the relationship between self-esteem stability, narcissism and psychological well-being. A total of 178 participants (77% female participated in this study. The average age of the participants was 20, with the ages ranging from 18 to 26 years. The participants completed the following scales and questionnaires: Narcissistic Personality Inventory (NPI, Psychological Well-being Scales (PWBS, Instability of Selfesteem scale (ISES and Rosenberg Self-esteem scale (RSES. The Rosenberg Self-esteem scale was used to measure both self-esteem level and self-esteem stability, which was defined as dispersion of self-esteem level in time. For the purpose of obtaining data on self-esteem stability, the participants were required complete the Rosenberg self-esteem scale for a sequence of 14 days, other measures were completed during the first day of participation in the study. The main effects for self-esteem level emerged for narcissism and psychological well-being, in both cases higher levels of self-esteem was associated to higher levels of narcissism and psychological well-being. Self-esteem stability additionally explained a significant proportion of variability in narcissism and psychological well-being. Self-esteem stability was negatively associated with higher levels of narcissism and positively associated with higher levels of psychological well-being, above and beyond the effect of self-esteem level. When comparing two different measures of self-esteem stability, the results revealed that people with higher level of narcissism tend to overestimate their self-esteem stability. The results were consistent with our hypotheses. The importance of considering both level and stability of self-esteem, limitations of the present study and possibilities for further research are

  3. Developmental and functional expression of miRNA-stability related genes in the nervous system.

    Science.gov (United States)

    de Sousa, Érica; Walter, Lais Takata; Higa, Guilherme Shigueto Vilar; Casado, Otávio Augusto Nocera; Kihara, Alexandre Hiroaki

    2013-01-01

    In the nervous system, control of gene expression by microRNAs (miRNAs) has been investigated in fundamental processes, such as development and adaptation to ambient demands. The action of these short nucleotide sequences on specific genes depends on intracellular concentration, which in turn reflects the balance of biosynthesis and degradation. Whereas mechanisms underlying miRNA biogenesis has been investigated in recent studies, little is known about miRNA-stability related proteins. We first detected two genes in the retina that have been associated to miRNA stability, XRN2 and PAPD4. These genes are highly expressed during retinal development, however with distinct subcellular localization. We investigated whether these proteins are regulated during specific phases of the cell cycle. Combined analyses of nuclei position in neuroblastic layer and labeling using anti-cyclin D1 revealed that both proteins do not accumulate in S or M phases of the cell cycle, being poorly expressed in progenitor cells. Indeed, XRN2 and PAPD4 were observed mainly after neuronal differentiation, since low expression was also observed in astrocytes, endothelial and microglial cells. XRN2 and PAPD4 are expressed in a wide variety of neurons, including horizontal, amacrine and ganglion cells. To evaluate the functional role of both genes, we carried out experiments addressed to the retinal adaptation in response to different ambient light conditions. PAPD4 is upregulated after 3 and 24 hours of dark- adaptation, revealing that accumulation of this protein is governed by ambient light levels. Indeed, the fast and functional regulation of PAPD4 was not related to changes in gene expression, disclosing that control of protein levels occurs by post-transcriptional mechanisms. Furthermore, we were able to quantify changes in PAPD4 in specific amacrine cells after dark -adaptation, suggesting for circuitry-related roles in visual perception. In summary, in this study we first described the

  4. Developmental and functional expression of miRNA-stability related genes in the nervous system.

    Directory of Open Access Journals (Sweden)

    Érica de Sousa

    Full Text Available In the nervous system, control of gene expression by microRNAs (miRNAs has been investigated in fundamental processes, such as development and adaptation to ambient demands. The action of these short nucleotide sequences on specific genes depends on intracellular concentration, which in turn reflects the balance of biosynthesis and degradation. Whereas mechanisms underlying miRNA biogenesis has been investigated in recent studies, little is known about miRNA-stability related proteins. We first detected two genes in the retina that have been associated to miRNA stability, XRN2 and PAPD4. These genes are highly expressed during retinal development, however with distinct subcellular localization. We investigated whether these proteins are regulated during specific phases of the cell cycle. Combined analyses of nuclei position in neuroblastic layer and labeling using anti-cyclin D1 revealed that both proteins do not accumulate in S or M phases of the cell cycle, being poorly expressed in progenitor cells. Indeed, XRN2 and PAPD4 were observed mainly after neuronal differentiation, since low expression was also observed in astrocytes, endothelial and microglial cells. XRN2 and PAPD4 are expressed in a wide variety of neurons, including horizontal, amacrine and ganglion cells. To evaluate the functional role of both genes, we carried out experiments addressed to the retinal adaptation in response to different ambient light conditions. PAPD4 is upregulated after 3 and 24 hours of dark- adaptation, revealing that accumulation of this protein is governed by ambient light levels. Indeed, the fast and functional regulation of PAPD4 was not related to changes in gene expression, disclosing that control of protein levels occurs by post-transcriptional mechanisms. Furthermore, we were able to quantify changes in PAPD4 in specific amacrine cells after dark -adaptation, suggesting for circuitry-related roles in visual perception. In summary, in this study we

  5. Testing the accuracy and stability of spectral methods in numerical relativity

    International Nuclear Information System (INIS)

    Boyle, Michael; Lindblom, Lee; Pfeiffer, Harald P.; Scheel, Mark A.; Kidder, Lawrence E.

    2007-01-01

    The accuracy and stability of the Caltech-Cornell pseudospectral code is evaluated using the Kidder, Scheel, and Teukolsky (KST) representation of the Einstein evolution equations. The basic 'Mexico City tests' widely adopted by the numerical relativity community are adapted here for codes based on spectral methods. Exponential convergence of the spectral code is established, apparently limited only by numerical roundoff error or by truncation error in the time integration. A general expression for the growth of errors due to finite machine precision is derived, and it is shown that this limit is achieved here for the linear plane-wave test

  6. Cue reliability and a landmark stability heuristic determine relative weighting between egocentric and allocentric visual information in memory-guided reach.

    Science.gov (United States)

    Byrne, Patrick A; Crawford, J Douglas

    2010-06-01

    It is not known how egocentric visual information (location of a target relative to the self) and allocentric visual information (location of a target relative to external landmarks) are integrated to form reach plans. Based on behavioral data from rodents and humans we hypothesized that the degree of stability in visual landmarks would influence the relative weighting. Furthermore, based on numerous cue-combination studies we hypothesized that the reach system would act like a maximum-likelihood estimator (MLE), where the reliability of both cues determines their relative weighting. To predict how these factors might interact we developed an MLE model that weighs egocentric and allocentric information based on their respective reliabilities, and also on an additional stability heuristic. We tested the predictions of this model in 10 human subjects by manipulating landmark stability and reliability (via variable amplitude vibration of the landmarks and variable amplitude gaze shifts) in three reach-to-touch tasks: an egocentric control (reaching without landmarks), an allocentric control (reaching relative to landmarks), and a cue-conflict task (involving a subtle landmark "shift" during the memory interval). Variability from all three experiments was used to derive parameters for the MLE model, which was then used to simulate egocentric-allocentric weighting in the cue-conflict experiment. As predicted by the model, landmark vibration--despite its lack of influence on pointing variability (and thus allocentric reliability) in the control experiment--had a strong influence on egocentric-allocentric weighting. A reduced model without the stability heuristic was unable to reproduce this effect. These results suggest heuristics for extrinsic cue stability are at least as important as reliability for determining cue weighting in memory-guided reaching.

  7. Linear Matrix Inequality Based Fuzzy Synchronization for Fractional Order Chaos

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2015-01-01

    Full Text Available This paper investigates fuzzy synchronization for fractional order chaos via linear matrix inequality. Based on generalized Takagi-Sugeno fuzzy model, one efficient stability condition for fractional order chaos synchronization or antisynchronization is given. The fractional order stability condition is transformed into a set of linear matrix inequalities and the rigorous proof details are presented. Furthermore, through fractional order linear time-invariant (LTI interval theory, the approach is developed for fractional order chaos synchronization regardless of the system with uncertain parameters. Three typical examples, including synchronization between an integer order three-dimensional (3D chaos and a fractional order 3D chaos, anti-synchronization of two fractional order hyperchaos, and the synchronization between an integer order 3D chaos and a fractional order 4D chaos, are employed to verify the theoretical results.

  8. OPTIMAL CONTROL FOR ELECTRIC VEHICLE STABILIZATION

    Directory of Open Access Journals (Sweden)

    MARIAN GAICEANU

    2016-01-01

    Full Text Available This main objective of the paper is to stabilize an electric vehicle in optimal manner to a step lane change maneuver. To define the mathematical model of the vehicle, the rigid body moving on a plane is taken into account. An optimal lane keeping controller delivers the adequate angles in order to stabilize the vehicle’s trajectory in an optimal way. Two degree of freedom linear bicycle model is adopted as vehicle model, consisting of lateral and yaw motion equations. The proposed control maintains the lateral stability by taking the feedback information from the vehicle transducers. In this way only the lateral vehicle’s dynamics are enough to considerate. Based on the obtained linear mathematical model the quadratic optimal control is designed in order to maintain the lateral stability of the electric vehicle. The numerical simulation results demonstrate the feasibility of the proposed solution.

  9. Relating β+ radionuclides' properties by order theory

    International Nuclear Information System (INIS)

    Quintero, N.Y.; Guillermo Restrepo; Cohen, I.M.; Universidad Tecnologica Nacional, Buenos Aires

    2013-01-01

    We studied 27 β + radionuclides taking into account some of their variants encoding information of their production, such as integral yield, threshold energy and energy of projectiles used to generate them; these radionuclides are of current use in clinical diagnostic imaging by positron emission tomography (PET). The study was conducted based on physical, physico-chemical, nuclear, dosimetric and quantum properties, which characterise the β + radionuclides selected, with the aim of finding meaningful relationships among them. In order to accomplish this objective the mathematical methodology known as formal concept analysis was employed. We obtained a set of logical assertions (rules) classified as implications and associations, for the set of β + radionuclides considered. Some of them show that low mass defect is related to high and medium values of maximum β + energy, and with even parity and low mean lives; all these parameters are associated to the dose received by a patient subjected to a PET analysis. (author)

  10. Short and long-term genome stability analysis of prokaryotic genomes.

    Science.gov (United States)

    Brilli, Matteo; Liò, Pietro; Lacroix, Vincent; Sagot, Marie-France

    2013-05-08

    Gene organization dynamics is actively studied because it provides useful evolutionary information, makes functional annotation easier and often enables to characterize pathogens. There is therefore a strong interest in understanding the variability of this trait and the possible correlations with life-style. Two kinds of events affect genome organization: on one hand translocations and recombinations change the relative position of genes shared by two genomes (i.e. the backbone gene order); on the other, insertions and deletions leave the backbone gene order unchanged but they alter the gene neighborhoods by breaking the syntenic regions. A complete picture about genome organization evolution therefore requires to account for both kinds of events. We developed an approach where we model chromosomes as graphs on which we compute different stability estimators; we consider genome rearrangements as well as the effect of gene insertions and deletions. In a first part of the paper, we fit a measure of backbone gene order conservation (hereinafter called backbone stability) against phylogenetic distance for over 3000 genome comparisons, improving existing models for the divergence in time of backbone stability. Intra- and inter-specific comparisons were treated separately to focus on different time-scales. The use of multiple genomes of a same species allowed to identify genomes with diverging gene order with respect to their conspecific. The inter-species analysis indicates that pathogens are more often unstable with respect to non-pathogens. In a second part of the text, we show that in pathogens, gene content dynamics (insertions and deletions) have a much more dramatic effect on genome organization stability than backbone rearrangements. In this work, we studied genome organization divergence taking into account the contribution of both genome order rearrangements and genome content dynamics. By studying species with multiple sequenced genomes available, we were

  11. Extrap L-1 experimental stability

    International Nuclear Information System (INIS)

    Brunsell, P.; Hellblom, G.; Karlsson, P.; Mazur, S.; Nordlund, P.; Scheffel, J.

    1990-01-01

    In the Extrap scheme a Z-pinch is stabilized by imposing a strongly inhomogeneous octupole magnetic field. This field is generated by four conductor rods, each carrying equal currents I v antiparallel to the plasma current I p itself. Theoretically, interchange stability is improved by the magnetic field, as well as long-wavelength kinks due to induced currents in the plasma and in the rods. Short wavelength kinks are, as in the 1-D pinch, stabilized by FLR and viscous-resistive effects. We have performed a set of experiments in the linear Extrap L-1 device (length 40 cm, plasma radius a 2 cm, rod distance 3 cm) in order to determine optimal performance in terms of confined current (5-20 kA) and stability during the discharge length (80 μs; of the order 100 Alfven times). In this paper we summarize our results from two types of experiments; with and without external axial magnetic field. The results are compared with theory in the final paragraph. (author) 5 figs

  12. Stability problems for linear hyperbolic systems

    International Nuclear Information System (INIS)

    Eckhoff, K.S.

    1975-05-01

    The stability properties for the trivial solution of a general linear hyperbolic system of partial differential equations of the first order are studied. It is shown that results may be obtained by studying the stability properties of certain systems of ordinary differential equations which can be constructed from the hyperbolic system (the so-called transport equations). In some cases the associated stability problem for the transport equations can in fact be shown to be equivalent to the stability problem for the hyperbolic system, but in general the transport equations will only give the necessary conditions for stability. (Auth.)

  13. SHARP: A Spatially Higher-order, Relativistic Particle-in-cell Code

    Energy Technology Data Exchange (ETDEWEB)

    Shalaby, Mohamad; Broderick, Avery E. [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1 (Canada); Chang, Philip [Department of Physics, University of Wisconsin-Milwaukee, 1900 E. Kenwood Boulevard, Milwaukee, WI 53211 (United States); Pfrommer, Christoph [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Lamberts, Astrid [Theoretical Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Puchwein, Ewald, E-mail: mshalaby@live.ca [Institute of Astronomy and Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom)

    2017-05-20

    Numerical heating in particle-in-cell (PIC) codes currently precludes the accurate simulation of cold, relativistic plasma over long periods, severely limiting their applications in astrophysical environments. We present a spatially higher-order accurate relativistic PIC algorithm in one spatial dimension, which conserves charge and momentum exactly. We utilize the smoothness implied by the usage of higher-order interpolation functions to achieve a spatially higher-order accurate algorithm (up to the fifth order). We validate our algorithm against several test problems—thermal stability of stationary plasma, stability of linear plasma waves, and two-stream instability in the relativistic and non-relativistic regimes. Comparing our simulations to exact solutions of the dispersion relations, we demonstrate that SHARP can quantitatively reproduce important kinetic features of the linear regime. Our simulations have a superior ability to control energy non-conservation and avoid numerical heating in comparison to common second-order schemes. We provide a natural definition for convergence of a general PIC algorithm: the complement of physical modes captured by the simulation, i.e., those that lie above the Poisson noise, must grow commensurately with the resolution. This implies that it is necessary to simultaneously increase the number of particles per cell and decrease the cell size. We demonstrate that traditional ways for testing for convergence fail, leading to plateauing of the energy error. This new PIC code enables us to faithfully study the long-term evolution of plasma problems that require absolute control of the energy and momentum conservation.

  14. Long term stability of power systems

    Energy Technology Data Exchange (ETDEWEB)

    Kundur, P; Gao, B [Powertech Labs. Inc., Surrey, BC (Canada)

    1994-12-31

    Power system long term stability is still a developing subject. In this paper we provide our perspectives and experiences related to long term stability. The paper begins with the description of the nature of the long term stability problem, followed by the discussion of issues related to the modeling and solution techniques of tools for long term stability analysis. Cases studies are presented to illustrate the voltage stability aspect and plant dynamics aspect of long term stability. (author) 20 refs., 11 figs.

  15. Stability of charge and orbital order in half-doped Y{sub 0.5}Ca{sub 0.5}MnO{sub 3} nanocrystallites

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Putul Malla, E-mail: putularun@gmail.com; Ghosh, Barnali, E-mail: barnali@bose.res.in; Raychaudhuri, A. K., E-mail: arup@bose.res.in [S N Bose National Centre for Basic Sciences, Unit for Nano Science, Department of Condensed Matter Physics and Materials Science (India); Kaushik, S. D.; Siruguri, V. [UGC-DAE Consortium for Scientific Research Mumbai Centre, R-5 Shed, Bhabha Atomic Research Centre (India)

    2013-04-15

    In this paper, we report a detailed study of the structure, magnetic, and electrical transport properties in nanocrystallites of hole-doped manganite Y{sub 0.5}Ca{sub 0.5}MnO{sub 3}, with the aim to study the effect of size reduction on the stability of the charge-orbital order and the antiferromagnetic spin order that are seen in the bulk samples of the half-doped manganite. The investigations have been done in the general context of investigating how size reduction affects competing interactions in complex oxides and thus, changes their ground state. The bulk sample of the material (average crystallite size {approx}1 {mu}m), with the smallest radius of the cation in A-site (Y), shows a robust charge and orbital ordered insulating state below the transition temperature near 290 K and an antiferromagnetic spin order at 110 K. The experiments carried out on well-characterized nanocrystalline samples, with average crystallite sizes down to 75 nm, establish that the size reduction changes the structural parameters, and the charge and orbital ordering are suppressed. However, the antiferromagnetic spin order (as revealed by neutron diffraction experiments carried out down to 2 K) persists in the nanocrystallites and co-exists with ferromagnetic order below 110 K. The nanocrystalline samples have significant lower resistivities (by few orders) compared to those of the bulk samples in the temperature range 10-300 K. This corroborates the formation of the ferromagnetic moments in the nanocrystallites.

  16. Lipid order, saturation and surface property relationships: a study of human meibum saturation.

    Science.gov (United States)

    Mudgil, Poonam; Borchman, Douglas; Yappert, Marta C; Duran, Diana; Cox, Gregory W; Smith, Ryan J; Bhola, Rahul; Dennis, Gary R; Whitehall, John S

    2013-11-01

    Tear film stability decreases with age however the cause(s) of the instability are speculative. Perhaps the more saturated meibum from infants may contribute to tear film stability. The meibum lipid phase transition temperature and lipid hydrocarbon chain order at physiological temperature (33 °C) decrease with increasing age. It is reasonable that stronger lipid-lipid interactions could stabilize the tear film since these interactions must be broken for tear break up to occur. In this study, meibum from a pool of adult donors was saturated catalytically. The influence of saturation on meibum hydrocarbon chain order was determined by infrared spectroscopy. Meibum is in an anhydrous state in the meibomian glands and on the surface of the eyelid. The influence of saturation on the surface properties of meibum was determined using Langmuir trough technology. Saturation of native human meibum did not change the minimum or maximum values of hydrocarbon chain order so at temperatures far above or below the phase transition of human meibum, saturation does not play a role in ordering or disordering the lipid hydrocarbon chains. Saturation did increase the phase transition temperature in human meibum by over 20 °C, a relatively high amount. Surface pressure-area studies showing the late take off and higher maximum surface pressure of saturated meibum compared to native meibum suggest that the saturated meibum film is quite molecularly ordered (stiff molecular arrangement) and elastic (molecules are able to rearrange during compression and expansion) compared with native meibum films which are more fluid agreeing with the infrared spectroscopic results of this study. In saturated meibum, the formation of compacted ordered islands of lipids above the surfactant layer would be expected to decrease the rate of evaporation compared to fluid and more loosely packed native meibum. Higher surface pressure observed with films of saturated meibum compared to native meibum

  17. Stability analysis of a class of fractional delay differential equations

    Indian Academy of Sciences (India)

    In this paper we analyse stability of nonlinear fractional order delay differential equations of the form D y ( t ) = a f ( y ( t − ) ) − by ( t ) , where D is a Caputo fractional derivative of order 0 < ≤ 1. We describe stability regions using critical curves. To explain the proposed theory, we discuss fractional order logistic ...

  18. Hydrogen peroxide stabilization in one-dimensional flow columns

    Science.gov (United States)

    Schmidt, Jeremy T.; Ahmad, Mushtaque; Teel, Amy L.; Watts, Richard J.

    2011-09-01

    Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H 2O 2 propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO.

  19. Age-related declines of stability in visual perceptual learning.

    Science.gov (United States)

    Chang, Li-Hung; Shibata, Kazuhisa; Andersen, George J; Sasaki, Yuka; Watanabe, Takeo

    2014-12-15

    One of the biggest questions in learning is how a system can resolve the plasticity and stability dilemma. Specifically, the learning system needs to have not only a high capability of learning new items (plasticity) but also a high stability to retain important items or processing in the system by preventing unimportant or irrelevant information from being learned. This dilemma should hold true for visual perceptual learning (VPL), which is defined as a long-term increase in performance on a visual task as a result of visual experience. Although it is well known that aging influences learning, the effect of aging on the stability and plasticity of the visual system is unclear. To address the question, we asked older and younger adults to perform a task while a task-irrelevant feature was merely exposed. We found that older individuals learned the task-irrelevant features that younger individuals did not learn, both the features that were sufficiently strong for younger individuals to suppress and the features that were too weak for younger individuals to learn. At the same time, there was no plasticity reduction in older individuals within the task tested. These results suggest that the older visual system is less stable to unimportant information than the younger visual system. A learning problem with older individuals may be due to a decrease in stability rather than a decrease in plasticity, at least in VPL. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. The significance of lower jaw position in relation to postural stability. Comparison of a premanufactured occlusal splint with the Dental Power Splint.

    Science.gov (United States)

    Ohlendorf, D; Riegel, M; Lin Chung, T; Kopp, S

    2013-01-01

    The purpose of this study was to investigate the effects on postural stability of two different lower jaw positions held in place by splints with eyes open and eyes closed. The postural stability in 21 healthy adult volunteers was investigated using two different sets of occlusal conditions with the lower jaw being at rest either with the eyes opened or closed. Two occlusal splints (standard splint and DPS splint) were used in order to maintain this lower jaw position. The balance behaviour was recorded using a balance platform. In a comparison of the habitual occlusion with the two occlusal splints, the balance posturographic values with the eyes opened fell between 7-9% and those for weight distribution with the eyes closed between 22-26% (with greater improvement being achieved with DPS) with the result that the variability in the range of fluctuations was reduced. The level of positioning accuracy deteriorated with the wearing of a splint between 13% with the DPS splint and 30% with the standard splint. Gender-specific differences of minor importance in relation to the positioning accuracy were recorded, with there being significant differences in the female participants (P≤0.00). An occlusal change in the stomatognathic system impacts on postural stability. Balance deficits seem to correlate with deteriorated body sway, which, according to the results, can be improved by a myocentric bite position using a DPS splint. This is more the case with the eyes closed than with the eyes opened.

  1. Direct calculation of self-consistent π bond orders in conjugated systems and pairing relations

    International Nuclear Information System (INIS)

    Castro, A.F.

    1982-01-01

    Pairing relations in excited states of conjugated systems which satisfy to a given symmetry with a Pariser-Parr-Pople-like (PPP) calculation are studied. Six π - electron systems are considered having a symmetry axis which does not cross π centers following a treatment which permits the direct obtainment of the bond order matrix based on Hall's method. Pairing relations are looked for, too, using particular solutions when U(3) groups is applied. Pyridazine molecules are used in order to test the results. (L.C.) [pt

  2. Impact of Model Detail of Synchronous Machines on Real-time Transient Stability Assessment

    DEFF Research Database (Denmark)

    Weckesser, Johannes Tilman Gabriel; Jóhannsson, Hjörtur; Østergaard, Jacob

    2013-01-01

    In this paper, it is investigated how detailed the model of a synchronous machine needs to be in order to assess transient stability using a Single Machine Equivalent (SIME). The results will show how the stability mechanism and the stability assessment are affected by the model detail. In order...... of the machine models is varied. Analyses of the results suggest that a 4th-order model may be sufficient to represent synchronous machines in transient stability studies....

  3. Error analysis of Newmark's method for the second order equation with inhomogeneous term

    International Nuclear Information System (INIS)

    Chiba, F.; Kako, T.

    2000-01-01

    For the second order time evolution equation with a general dissipation term, we introduce a recurrence relation of Newmark's method. Deriving an energy inequality from this relation, we consider the stability and the convergence criteria of Newmark's method. We treat a dissipation term under the assumption that the coefficient-damping matrix is constant in time and non-negative. We can relax however the assumptions for the dissipation and the rigidity matrices to be arbitrary symmetric matrices. (author)

  4. Impact of leakage delay on bifurcation in high-order fractional BAM neural networks.

    Science.gov (United States)

    Huang, Chengdai; Cao, Jinde

    2018-02-01

    The effects of leakage delay on the dynamics of neural networks with integer-order have lately been received considerable attention. It has been confirmed that fractional neural networks more appropriately uncover the dynamical properties of neural networks, but the results of fractional neural networks with leakage delay are relatively few. This paper primarily concentrates on the issue of bifurcation for high-order fractional bidirectional associative memory(BAM) neural networks involving leakage delay. The first attempt is made to tackle the stability and bifurcation of high-order fractional BAM neural networks with time delay in leakage terms in this paper. The conditions for the appearance of bifurcation for the proposed systems with leakage delay are firstly established by adopting time delay as a bifurcation parameter. Then, the bifurcation criteria of such system without leakage delay are successfully acquired. Comparative analysis wondrously detects that the stability performance of the proposed high-order fractional neural networks is critically weakened by leakage delay, they cannot be overlooked. Numerical examples are ultimately exhibited to attest the efficiency of the theoretical results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Effects of anticaking agents and relative humidity on the physical and chemical stability of powdered vitamin C.

    Science.gov (United States)

    Lipasek, Rebecca A; Taylor, Lynne S; Mauer, Lisa J

    2011-09-01

    Vitamin C is an essential nutrient that is widely used by the food industry in the powder form for both its nutritional and functional properties. However, vitamin C is deliquescent, and deliquescence has been linked to physical and chemical instabilities. Anticaking agents are often added to powder systems to delay or prevent caking, but little is known about their effect on the chemical stability of powders. In this study, various anticaking agents (calcium phosphate, calcium silicate, calcium stearate, corn starch, and silicon dioxide) were combined with sodium ascorbate at 2% and 50% w/w ratios and stored at various relative humidities (23%, 43%, 64%, 75%, 85%, and 98% RHs). Chemical and physical stability and moisture sorption were monitored over time. Additionally, saturated solution samples were stored at various pHs to determine the effect of surface pH and dissolution on the vitamin degradation rate. Storage RH, time, and anticaking agent type and ratio all significantly affected (P vitamin C stability. Silicon dioxide and calcium silicate (50% w/w) and calcium stearate (at both ratios) were the only anticaking agents to improve the physical stability of powdered sodium ascorbate while none of the anticaking agents improved its chemical stability. However, corn starch and calcium stearate had the least adverse effect on chemical stability. Dissolution rate and pH were also important factors affecting the chemical and physical stability of the powders. Therefore, monitoring storage environmental conditions and anticaking agent usage are important for understanding the stability of vitamin C. Anticaking agent type and ratio significantly affected the physical and chemical stability of vitamin C over time and over a range of RHs. No anticaking agent improved the chemical stability of the vitamin, and most caused an increase in chemical degradation even if physical stability was improved. It is possible that anticaking agents would greatly affect other

  6. Personality Stability from Childhood to Midlife: Relating Teachers’ Assessments in Elementary School to Observer- and Self-Ratings 40 Years Later

    Science.gov (United States)

    Edmonds, Grant W.; Goldberg, Lewis R.; Hampson, Sarah E.; Barckley, Maureen

    2013-01-01

    We report on the longitudinal stability of personality traits across an average 40 years in the Hawaii Personality and Health Cohort relating childhood teacher assessments of personality to adult self- and observer- reports. Stabilities based on self-ratings in adulthood were compared to those measured by the Structured Interview for the Five-Factor Model (SIFFM; Trull & Widiger, 1997), and trait ratings completed by interviewers. Although convergence between self-reports and observer-ratings was modest, childhood traits demonstrated similar levels of stability across methods in adulthood. Extraversion and Conscientiousness generally showed higher stabilities, whereas Neuroticism showed none. For Agreeableness and Intellect/Openness, stability was highest when assessed with observer-ratings. These findings are discussed in terms of differences in trait evaluativeness and observability across measurement methods. PMID:24039315

  7. On finite larmor radius stabilization of Z-pinches

    International Nuclear Information System (INIS)

    Hellsten, T.

    1982-12-01

    Finite Larmor radius stabilization of Z-pinches is discussed. Stability criteria can be derived for a class of equilibria having constant mass and current density. The internal modes can be stabilized provided the line density not exceed a critical value of the order of 10 18 ions/m. (Author)

  8. Stability analysis of a class of fractional delay differential equations

    Indian Academy of Sciences (India)

    Abstract. In this paper we analyse stability of nonlinear fractional order delay differential equa- tions of the form Dα y(t) = af (y(t − τ )) − by(t), where Dα is a Caputo fractional derivative of order 0 < α ≤ 1. We describe stability regions using critical curves. To explain the proposed theory, we discuss fractional order logistic ...

  9. Synthetic Jets Flow Control on a vertical stabilizer

    Science.gov (United States)

    Rathay, Nicholas; Boucher, Matthew; Amitay, Michael

    2011-11-01

    The vertical stabilizer on most commercial transport aircraft is much larger than required for stability and control. The tail is significantly oversized in order to maintain controllability in the event of asymmetric engine failure and meet flying qualities requirements related to dynamic motion. Using aerodynamic flow control techniques, it may be possible to reduce the size of the tail while maintaining similar control authority during inclement flight conditions. Reducing the size of the tail decreases the weight and the drag of the airplane, which results in considerable savings in fuel costs. In this work, it is shown that synthetic jet (zero-net-mass-flux) actuators are capable of reattaching the separated flow on the rudder and augmenting the performance of the stabilizer. Experiments were conducted in an open-return wind tunnel on a 1/25th scale model of a vertical stabilizer and a partial fuselage section. The surface pressure, aerodynamic loads and data acquired with a Stereo PIV system were used to investigate the effectiveness of this technology as well as provide a more detailed analysis of the flowfield and showed that the synthetic jets are capable of augmenting the side-force by up to 20%.

  10. Stabilizing effect of epoxidized sunflower oil as a secondary stabilizer for Ca/Hg stabilized PVC

    Directory of Open Access Journals (Sweden)

    2008-01-01

    Full Text Available Unsaturated triglyceride oil sunflower was epoxidized and characterized by chemical and spectroscopic methods. Epoxidized sunflower oil (ESO was used as an organic thermal co-stabilizer for rigid poly(vinyl chloride (PVC in the presence of tricalcium dicitrate (Ca3(C6H5O72 and mercury (II acetate (Hg(CH3COO2. The thermo-oxidative degradation of PVC was studied in the presence of these ternary stabilizer systems at 170, 180, 190 and 200°C in N2 atmosphere. The effects of metal carboxylate combination Ca/Hg in the absence and in the presence of epoxidized sunflower oil on static heat treatment of PVC have been studied. The formation of polyene sequences was investigated by UV-visible and FT-IR spectroscopy and by comparing viscosity data obtained in the presence and in the absence of the additives. It was found that the additives retard the rate of degradation and reduce the extent of polymer chain scission associated with the thermal degradation of poly(vinyl chloride. Synergistic effects were found when stabilizer was blended in 50:50 weight ratios with either. It was found that ESO exerted a stabilizing effect on the degradation of PVC. The activation energy for degraded PVC in absence of stabilizers was 38.6 kJ•mol–1 and in the presence of Ca/Hg and Ca/Hg/ESO were 53.3 and 64.7 kJ•mol–1 respectively. In order of compare the efficiency of the epoxidized sunflower oil with these metal soap stabilizers, thermal stabilities were evaluated on the basis of evolved hydrogen chloride determined by conductometry technique and degree of discoloration are discussed.

  11. Convergence order vs. parallelism in the numerical simulation of the bidomain equations

    International Nuclear Information System (INIS)

    Sharomi, Oluwaseun; Spiteri, Raymond J

    2012-01-01

    The propagation of electrical activity in the human heart can be modelled mathematically by the bidomain equations. The bidomain equations represent a multi-scale reaction-diffusion model that consists of a set of ordinary differential equations governing the dynamics at the cellular level coupled with a set of partial differential equations governing the dynamics at the tissue level. Significant computation is generally required to generate clinically useful data from the bidomain equations. Contemporary developments in computer architecture, in particular multi- and many-core computers and graphics processing units, have made such computations feasible. However, the zeal to take advantage to parallel architectures has typically caused another important aspect of numerical methods for the solution of differential equations to be overlooked, namely the convergence order. It is well known that higher-order methods are generally more efficient than lower-order ones when solutions are smooth and relatively high accuracy is desired. In these situations, serial implementations of high-order methods may remain surprisingly competitive with parallel implementations of low-order methods. In this paper, we examine the effect of order on the numerical solution of the bidomain equations in parallel. We find that high-order methods, in particular high-order time-integration methods with relatively better stability properties, tend to outperform their low-order counterparts, even when the latter are run in parallel. In other words, increasing integration order often trumps increasing available computational resources, especially when relatively high accuracy is desired.

  12. Power system stabilizer control for wind power to enhance power system stability

    OpenAIRE

    Domínguez García, José Luís; Gomis Bellmunt, Oriol; Bianchi, Fernando Daniel; Sumper, Andreas

    2011-01-01

    The paper presents a small signal stability analysis for power systems with wind farm interaction. Power systems have damping oscillation modes that can be excited by disturbance or fault in the grid. The power converters of the wind farms can be used to reduce these oscillations and make the system more stable. These ideas are explored to design a power system stabilized (PSS) for a network with conventional generators and a wind farm in order to increase the damping of the oscillation...

  13. High-order upwind schemes for the wave equation on overlapping grids: Maxwell's equations in second-order form

    Science.gov (United States)

    Angel, Jordan B.; Banks, Jeffrey W.; Henshaw, William D.

    2018-01-01

    High-order accurate upwind approximations for the wave equation in second-order form on overlapping grids are developed. Although upwind schemes are well established for first-order hyperbolic systems, it was only recently shown by Banks and Henshaw [1] how upwinding could be incorporated into the second-order form of the wave equation. This new upwind approach is extended here to solve the time-domain Maxwell's equations in second-order form; schemes of arbitrary order of accuracy are formulated for general curvilinear grids. Taylor time-stepping is used to develop single-step space-time schemes, and the upwind dissipation is incorporated by embedding the exact solution of a local Riemann problem into the discretization. Second-order and fourth-order accurate schemes are implemented for problems in two and three space dimensions, and overlapping grids are used to treat complex geometry and problems with multiple materials. Stability analysis of the upwind-scheme on overlapping grids is performed using normal mode theory. The stability analysis and computations confirm that the upwind scheme remains stable on overlapping grids, including the difficult case of thin boundary grids when the traditional non-dissipative scheme becomes unstable. The accuracy properties of the scheme are carefully evaluated on a series of classical scattering problems for both perfect conductors and dielectric materials in two and three space dimensions. The upwind scheme is shown to be robust and provide high-order accuracy.

  14. General relativity and gauge gravity theories of higher order

    International Nuclear Information System (INIS)

    Konopleva, N.P.

    1998-01-01

    It is a short review of today's gauge gravity theories and their relations with Einstein General Relativity. The conceptions of construction of the gauge gravity theories with higher derivatives are analyzed. GR is regarded as the gauge gravity theory corresponding to the choice of G ∞4 as the local gauge symmetry group and the symmetrical tensor of rank two g μν as the field variable. Using the mathematical technique, single for all fundamental interactions (namely variational formalism for infinite Lie groups), we can obtain Einstein's theory as the gauge theory without any changes. All other gauge approaches lead to non-Einstein theories of gravity. But above-mentioned mathematical technique permits us to construct the gauge gravity theory of higher order (for instance SO (3,1)-gravity) so that all vacuum solutions of Einstein equations are the solutions of the SO (3,1)-gravity theory. The structure of equations of SO(3,1)-gravity becomes analogous to Weeler-Misner geometrodynamics one

  15. Feasibility and Stability in Normative Political Philosophy

    DEFF Research Database (Denmark)

    Lægaard, Sune

    2006-01-01

    Arguments from stability for liberal nationalism rely on considerations about conditions for the feasibility or stability of liberal political ideals and factual claims about the circumstances under which these conditions are fulfilled in order to argue for nationalist conclusions. Such reliance ...

  16. Dynamic stability and failure modes of slopes in discontinuous rock mass

    International Nuclear Information System (INIS)

    Shimizu, Yasuhiro; Aydan, O.; Ichikawa, Yasuaki; Kawamoto, Toshikazu.

    1988-01-01

    The stability of rock slopes during earthquakes are of great concern in rock engineering works such as highway, dam, and nuclear power station constructions. As rock mass in nature is usually discontinuous, the stability of rock slopes will be geverned by the spatial distribution of discontinuities in relation with the geometry of slope and their mechanical properties rather than the rock element. The authors have carried out some model tests on discontinuous rock slopes using three different model tests techniques in order to investigate the dynamic behaviour and failure modes of the slopes in discontinuous rock mass. This paper describes the findings and observations made on model rock slopes with various discontinuity patterns and slope geometry. In addition some stability criterions are developed and the calculated results are compared with those of experiments. (author)

  17. Effect of the relative shift between the electron density and temperature pedestal position on the pedestal stability in JET-ILW and comparison with JET-C

    Science.gov (United States)

    Stefanikova, E.; Frassinetti, L.; Saarelma, S.; Loarte, A.; Nunes, I.; Garzotti, L.; Lomas, P.; Rimini, F.; Drewelow, P.; Kruezi, U.; Lomanowski, B.; de la Luna, E.; Meneses, L.; Peterka, M.; Viola, B.; Giroud, C.; Maggi, C.; contributors, JET

    2018-05-01

    The electron temperature and density pedestals tend to vary in their relative radial positions, as observed in DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) and ASDEX Upgrade (Dunne et al 2017 Plasma Phys. Control. Fusion 59 14017). This so-called relative shift has an impact on the pedestal magnetohydrodynamic (MHD) stability and hence on the pedestal height (Osborne et al 2015 Nucl. Fusion 55 063018). The present work studies the effect of the relative shift on pedestal stability of JET ITER-like wall (JET-ILW) baseline low triangularity (δ) unseeded plasmas, and similar JET-C discharges. As shown in this paper, the increase of the pedestal relative shift is correlated with the reduction of the normalized pressure gradient, therefore playing a strong role in pedestal stability. Furthermore, JET-ILW tends to have a larger relative shift compared to JET carbon wall (JET-C), suggesting a possible role of the plasma facing materials in affecting the density profile location. Experimental results are then compared with stability analysis performed in terms of the peeling-ballooning model and with pedestal predictive model EUROPED (Saarelma et al 2017 Plasma Phys. Control. Fusion). Stability analysis is consistent with the experimental findings, showing an improvement of the pedestal stability, when the relative shift is reduced. This has been ascribed mainly to the increase of the edge bootstrap current, and to minor effects related to the increase of the pedestal pressure gradient and narrowing of the pedestal pressure width. Pedestal predictive model EUROPED shows a qualitative agreement with experiment, especially for low values of the relative shift.

  18. Modulation stability and dispersive optical soliton solutions of higher order nonlinear Schrödinger equation and its applications in mono-mode optical fibers

    Science.gov (United States)

    Arshad, Muhammad; Seadawy, Aly R.; Lu, Dianchen

    2018-01-01

    In mono-mode optical fibers, the higher order non-linear Schrödinger equation (NLSE) describes the propagation of enormously short light pulses. We constructed optical solitons and, solitary wave solutions of higher order NLSE mono-mode optical fibers via employing modified extended mapping method which has important applications in Mathematics and physics. Furthermore, the formation conditions are also given on parameters in which optical bright and dark solitons can exist for this media. The moment of the obtained solutions are also given graphically, that helps to realize the physical phenomena's of this model. The modulation instability analysis is utilized to discuss the model stability, which verifies that all obtained solutions are exact and stable. Many other such types of models arising in applied sciences can also be solved by this reliable, powerful and effective method. The method can also be functional to other sorts of higher order nonlinear problems in contemporary areas of research.

  19. Stacking stability of MoS2 bilayer: An ab initio study

    International Nuclear Information System (INIS)

    Tao Peng; Guo Huai-Hong; Yang Teng; Zhang Zhi-Dong

    2014-01-01

    The study of the stacking stability of bilayer MoS 2 is essential since a bilayer has exhibited advantages over single layer MoS 2 in many aspects for nanoelectronic applications. We explored the relative stability, optimal sliding path between different stacking orders of bilayer MoS 2 , and (especially) the effect of inter-layer stress, by combining first-principles density functional total energy calculations and the climbing-image nudge-elastic-band (CI-NEB) method. Among five typical stacking orders, which can be categorized into two kinds (I: AA, AB and II: AA', AB', A'B), we found that stacking orders with Mo and S superposing from both layers, such as AA' and AB, is more stable than the others. With smaller computational efforts than potential energy profile searching, we can study the effect of inter-layer stress on the stacking stability. Under isobaric condition, the sliding barrier increases by a few eV/(ucGPa) from AA' to AB', compared to 0.1 eV/(ucGPa) from AB to [AB]. Moreover, we found that interlayer compressive stress can help enhance the transport properties of AA'. This study can help understand why inter-layer stress by dielectric gating materials can be an effective means to improving MoS 2 on nanoelectronic applications. (condensed matter: structural, mechanical, and thermal properties)

  20. Stability of mechanically alloyed vacancy ordered phase in Al{sub 70}Cu{sub 15}Ni{sub 15} alloy during annealing

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Thakur Prasad; Tiwari, Radhey Shyam; Srivastava, Onkar Nath [Department of Physics, Banaras Hindu University, Varanasi-221 005 (India); Mukhopadhyay, Nilay Krishna, E-mail: hepons@yahoo.co, E-mail: yadavtp@gmail.co [Department of Metallurgical Engineering, Institute of Technology, Banaras Hindu University, Varanasi-221 005 (India)

    2010-04-01

    A nano {tau}{sub 3} vacancy-ordered phase in the Al-Cu-Ni alloy system has been synthesized with a composition close to Al{sub 70}Cu{sub 15}Ni{sub 15} by mechanical alloying a mixture of elemental powder in a high-energy ball mill by varying milling time from 10 to 100 hours. The stability of nano-crystalline {tau}{sub 3} vacancy-ordered phase has been studied under thermal annealing in vacuum as well as in air. The x-ray diffraction and transmission electron microscopy techniques were employed for characterization of the milled and annealed samples. The powder after 100 h of milling was found to contain mostly nano {tau}{sub 3} phase with the partial ordering, and with crystallite sizes in the range of 10-20 nm along with a lattice strain of {approx}0.67 %. The milled powder, after annealing in vacuum at 700 {sup 0}C for 60 h, revealed the formation of a strain-free and ordered {tau}{sub 3} phase with a crystallite size of 80 nm, indicating grain coarsening. It is interesting to note that the milled powder annealed in air at 700 {sup 0}C for 60 h showed the formation of (Cu,Ni)Al{sub 2}O{sub 4} type spinel phase with the lattice parameter of 8.1 A and the lattice strain as 0.52 %. The average grain size of spinel phase was found to be {approx} 40 nm.

  1. Reliability criteria for voltage stability

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Carson W; Silverstein, Brian L [Bonneville Power Administration, Portland, OR (United States)

    1994-12-31

    In face of costs pressures, there is need to allocate scare resources more effectively in order to achieve voltage stability. This naturally leads to development of probabilistic criteria and notions of rick management. In this paper it is presented a discussion about criteria for long term voltage stability limited to the case in which the time frames are topically several minutes. (author) 14 refs., 1 fig.

  2. Moment stability for a predator–prey model with parametric dichotomous noises

    International Nuclear Information System (INIS)

    Jin Yan-Fei

    2015-01-01

    In this paper, we investigate the solution moment stability for a Harrison-type predator–prey model with parametric dichotomous noises. Using the Shapiro–Loginov formula, the equations for the first-order and second-order moments are obtained and the corresponding stable conditions are given. It is found that the solution moment stability depends on the noise intensity and correlation time of noise. The first-order and second-order moments become unstable with the decrease of correlation time. That is, the dichotomous noise can improve the solution moment stability with respect to Gaussian white noise. Finally, some numerical results are presented to verify the theoretical analyses. (paper)

  3. Robust Fuzzy Control for Fractional-Order Uncertain Hydroturbine Regulating System with Random Disturbances

    OpenAIRE

    Fengjiao Wu; Guitao Zhang; Zhengzhong Wang

    2016-01-01

    The robust fuzzy control for fractional-order hydroturbine regulating system is studied in this paper. First, the more practical fractional-order hydroturbine regulating system with uncertain parameters and random disturbances is presented. Then, on the basis of interval matrix theory and fractional-order stability theorem, a fuzzy control method is proposed for fractional-order hydroturbine regulating system, and the stability condition is expressed as a group of linear matrix inequalities. ...

  4. Quantized flocking control for second-order multiple agents with obstacle avoidance

    Directory of Open Access Journals (Sweden)

    Chunguang Li

    2016-01-01

    Full Text Available A quantized flocking control for a group of second-order multiple agents with obstacle avoidance is proposed to address the problem of the exchange of information needed for quantification. With a reasonable assumption, a logarithmic or uniform quantizer is used for the exchange of relative position and velocity information between adjacent agents and the virtual leader, moving at a steady speed along a straight line, and a distributed flocking algorithm with obstacle avoidance capability is designed based on the quantitative information. The Lyapunov stability criterion of nonsmooth systems and the invariance principle are used to prove the stability of these systems. The simulations and experiments are presented to demonstrate the feasibility and effectiveness of the proposed approach.

  5. How can we strengthen students’ social relations in order to reduce school dropout?

    DEFF Research Database (Denmark)

    Ingholt, Liselotte; Sørensen, Betina Bang; Andersen, Susan

    2015-01-01

    on ethnographic methods, including 22 qualitative interviews with students 17-19 years old and fieldwork with participant observations at four vocational schools over 40 days, including informal interviews and discussion meetings with managers, teachers, counselors and students. As part of the fieldwork, four......BACKGROUND: This article describes the rationale and contents of an intervention program aimed at strengthening students' social relations in order to reduce dropout from vocational schools in Denmark. Taking its theoretical cue from the concept of 'social participation', a qualitative study...... was performed to investigate the specific relationships between the social environment within the schools and the institutional structures in order to analyse reasons for school dropout and their relation to well-being, cigarette smoking and substance use. METHODS: The development study was based...

  6. Higher order structural effects stabilizing the reverse watson-crick guanine-cytosine base pair in functional RNAs

    KAUST Repository

    Chawla, Mohit; Abdel-Azeim, Safwat; Oliva, Romina; Cavallo, Luigi

    2013-01-01

    of the Guanine can increase its stability. Herein, we extend our survey and report on other H-bonding interactions that can increase the stability of this base pair. To this aim, we performed a bioinformatics search of the PDB to locate all the occurencies of G

  7. Critical angular momentum dependence of the fission barriers and the stability of superheavy nuclei

    International Nuclear Information System (INIS)

    Magda, M.T.; Sandulescu, A.

    1978-10-01

    Measured complete fusion and evaporation cross section data are used to determine the critical angular momenta for which the fission barriers are vanishing in the region of nuclei with Z = 102 - 116. It is shown that, in order to fit these data, larger values of the critical angular momenta are obtained for superheavy nuclei (Z = 110 - 112) than for heavy ones (Z = 102 - 107), which indicates a relatively higher stability against fission for superheavy nuclei, in agreement with the theoretically predicted island of stability. (author)

  8. The long-term stability of self-esteem: its time-dependent decay and nonzero asymptote.

    Science.gov (United States)

    Kuster, Farah; Orth, Ulrich

    2013-05-01

    How stable are individual differences in self-esteem? We examined the time-dependent decay of rank-order stability of self-esteem and tested whether stability asymptotically approaches zero or a nonzero value across long test-retest intervals. Analyses were based on 6 assessments across a 29-year period of a sample of 3,180 individuals aged 14 to 102 years. The results indicated that, as test-retest intervals increased, stability exponentially decayed and asymptotically approached a nonzero value (estimated as .43). The exponential decay function explained a large proportion of variance in observed stability coefficients, provided a better fit than alternative functions, and held across gender and for all age groups from adolescence to old age. Moreover, structural equation modeling of the individual-level data suggested that a perfectly stable trait component underlies stability of self-esteem. The findings suggest that the stability of self-esteem is relatively large, even across very long periods, and that self-esteem is a trait-like characteristic.

  9. Electrochemical stability of ionic clathrate hydrates and their structural consideration

    International Nuclear Information System (INIS)

    Lee, Wonhee; Lim, Dongwook; Lee, Huen

    2013-01-01

    Although electrochemical stability is an essential factor in relation to the potential applications of ionic clathrate hydrates to solid electrolytes, most studies regarding the proton conductors have focused on their ionic conductivity and thermal stability. Solid electrolytes in various electrochemical devices have to endure the applied potentials; thus, we examined the linear sweep voltammograms of various tetraalkylammonium hydroxide hydrates in order to shed light on the trend of electrochemical stability depending on the hydrate structure. We revealed that the electrochemical stability of Me 4 NOH hydrates is mainly affected by both their ionic concentration and cage occupancy. In particular, the true clathrate structures of β-Me 4 NOH hydrates are more electrochemically stable than their α-forms that possess partially broken hydrogen bonds. We also observed that the binary THF–Pr 4 NOH and pure Bu 4 NOH clathrate hydrates exhibit greater electrochemical stability than those of pure Me 4 NOH hydrates having lower or similar ionic concentrations. These results are considered to arise from the fact that each of the Pr 4 N + and Bu 4 N + ions occupies an extended space comprising four cages, which leads to stabilization of the larger unit, whereas a Me 4 N + ion is completely included only in one cage

  10. Group-ICA model order highlights patterns of functional brain connectivity

    Directory of Open Access Journals (Sweden)

    Ahmed eAbou Elseoud

    2011-06-01

    Full Text Available Resting-state networks (RSNs can be reliably and reproducibly detected using independent component analysis (ICA at both individual subject and group levels. Altering ICA dimensionality (model order estimation can have a significant impact on the spatial characteristics of the RSNs as well as their parcellation into sub-networks. Recent evidence from several neuroimaging studies suggests that the human brain has a modular hierarchical organization which resembles the hierarchy depicted by different ICA model orders. We hypothesized that functional connectivity between-group differences measured with ICA might be affected by model order selection. We investigated differences in functional connectivity using so-called dual-regression as a function of ICA model order in a group of unmedicated seasonal affective disorder (SAD patients compared to normal healthy controls. The results showed that the detected disease-related differences in functional connectivity alter as a function of ICA model order. The volume of between-group differences altered significantly as a function of ICA model order reaching maximum at model order 70 (which seems to be an optimal point that conveys the largest between-group difference then stabilized afterwards. Our results show that fine-grained RSNs enable better detection of detailed disease-related functional connectivity changes. However, high model orders show an increased risk of false positives that needs to be overcome. Our findings suggest that multilevel ICA exploration of functional connectivity enables optimization of sensitivity to brain disorders.

  11. On the relation between Jahn-Teller ordering and charge ordering

    International Nuclear Information System (INIS)

    Eijndhoven, J.C.M van.

    1978-01-01

    This thesis compares the structures of KCusup(II)F 3 and Cs 2 Ausup(I)Ausup(III)Cl 6 . Both compounds have a structure that can be thought to result from a deformation of the cubic perovskite structure. The deformation of KCusup(II)F 3 is a result of a cooperative Jahn-Teller effect and the deformation of Cs 2 Ausup(I)Ausup(III)Cl 6 results in two sublattices. The structures of both compounds result from a continuous phase transition from the cubic pervskite structure due to a deformation of symmetry. Using local coordinates and a calculation of the electron-lattice interaction in a static approximation, four structure types were derived. One is the structure of Cs 2 AuAuCl 6 at ambient temperature and pressure and the second contains a group of structures corresponding to the structures found for KCuF 3 . The third structure type was recently suggested for Cs 2 AuAuCl 6 under pressure and the fourth has not been found experimentally. Two types show a Jahn-Teller ordering and the other two charge ordering (Auth./C.F.)

  12. Structure and stability insights into tumour suppressor p53 evolutionary related proteins.

    Directory of Open Access Journals (Sweden)

    Bruno Pagano

    Full Text Available The p53 family of genes and their protein products, namely, p53, p63 and p73, have over one billion years of evolutionary history. Advances in computational biology and genomics are enabling studies of the complexities of the molecular evolution of p53 protein family to decipher the underpinnings of key biological conditions spanning from cancer through to various metabolic and developmental disorders and facilitate the design of personalised medicines. However, a complete understanding of the inherent nature of the thermodynamic and structural stability of the p53 protein family is still lacking. This is due, to a degree, to the lack of comprehensive structural information for a large number of homologous proteins and to an incomplete knowledge of the intrinsic factors responsible for their stability and how these might influence function. Here we investigate the thermal stability, secondary structure and folding properties of the DNA-binding domains (DBDs of a range of proteins from the p53 family using biophysical methods. While the N- and the C-terminal domains of the p53 family show sequence diversity and are normally targets for post-translational modifications and alternative splicing, the central DBD is highly conserved. Together with data obtained from Molecular Dynamics simulations in solution and with structure based homology modelling, our results provide further insights into the molecular properties of evolutionary related p53 proteins. We identify some marked structural differences within the p53 family, which could account for the divergence in biological functions as well as the subtleties manifested in the oligomerization properties of this family.

  13. The concept of stability in numerical mathematics

    CERN Document Server

    Hackbusch, Wolfgang

    2014-01-01

    In this book, the author compares the meaning of stability in different subfields of numerical mathematics.  Concept of Stability in numerical mathematics opens by examining the stability of finite algorithms. A more precise definition of stability holds for quadrature and interpolation methods, which the following chapters focus on. The discussion then progresses to the numerical treatment of ordinary differential equations (ODEs). While one-step methods for ODEs are always stable, this is not the case for hyperbolic or parabolic differential equations, which are investigated next. The final chapters discuss stability for discretisations of elliptic differential equations and integral equations. In comparison among the subfields we discuss the practical importance of stability and the possible conflict between higher consistency order and stability.  

  14. Stability of ideal and resistive modes in cylindrical plasmas with resistive walls and plasma rotation

    International Nuclear Information System (INIS)

    Bondeson, A.; Xie, H.X.

    1996-01-01

    The stabilization of cylindrical plasmas by resistive walls combined with plasma rotation is analyzed. Perturbations with a single mode rational surface q=m/n in a finitely conducting plasma are treated by the resistive kink dispersion relation of Coppi. The possibilities for stabilization of ideal and resistive instabilities are explored systematically in different regions of parameter space. The study confirms that an ideal instability can be stabilized by a close-fitting wall and a rotation velocity of the order of resistive growth rate. However, the region in parameter space where such stabilization occurs is very small and appears to be difficult to exploit in experiments. The overall conclusion from the cylindrical plasma model is that resistive modes can readily be wall stabilized, whereas complete wall stabilization is hard to achieve for plasmas that are ideally unstable with the wall at infinity. 26 refs, 5 figs

  15. Identification of the reduced order models of a BWR reactor; Identificacion de modelos de orden reducido de un reactor BWR

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez S, A. [UNAM, Laboratorio de Analisis de Ingenieria de Reactores Nucleares, DEPFI, Campus Morelos, en IMTA Jiutepec, Morelos (Mexico)]. e-mail: augusto@correo.unam.mx

    2004-07-01

    The present work has as objective to analyze the relative stability of a BWR type reactor. It is analyzed that so adaptive it turns out to identify the parameters of a model of reduced order so that this it reproduces a condition of given uncertainty. This will take of a real fact happened in the La Salle plant under certain operation conditions of power and flow of coolant. The parametric identification is carried out by means of an algorithm of recursive least square and an Output Error model (Output Error), measuring the output power of the reactor when the instability is present, and considering that it is produced by a change in the reactivity of the system in the same way that a sign of type step. Also it is carried out an analytic comparison of the relative stability, analyzing two types of answers: the original answer of the uncertainty of the reactor vs. the obtained response identifying the parameters of the model of reduced order, reaching the conclusion that it is very viable to adapt a model of reduced order to study the stability of a reactor, under the only condition to consider that the dynamics of the reactivity is of step type. (Author)

  16. Solar Dynamic Power System Stability Analysis and Control

    Science.gov (United States)

    Momoh, James A.; Wang, Yanchun

    1996-01-01

    The objective of this research is to conduct dynamic analysis, control design, and control performance test of solar power system. Solar power system consists of generation system and distribution network system. A bench mark system is used in this research, which includes a generator with excitation system and governor, an ac/dc converter, six DDCU's and forty-eight loads. A detailed model is used for modeling generator. Excitation system is represented by a third order model. DDCU is represented by a seventh order system. The load is modeled by the combination of constant power and constant impedance. Eigen-analysis and eigen-sensitivity analysis are used for system dynamic analysis. The effects of excitation system, governor, ac/dc converter control, and the type of load on system stability are discussed. In order to improve system transient stability, nonlinear ac/dc converter control is introduced. The direct linearization method is used for control design. The dynamic analysis results show that these controls affect system stability in different ways. The parameter coordination of controllers are recommended based on the dynamic analysis. It is concluded from the present studies that system stability is improved by the coordination of control parameters and the nonlinear ac/dc converter control stabilize system oscillation caused by the load change and system fault efficiently.

  17. Sludge Stabilization Campaign blend plan

    International Nuclear Information System (INIS)

    De Vries, M.L.

    1994-01-01

    This sludge stabilization blend plan documents the material to be processed and the order of processing for the FY95 Sludge Stabilization Campaign. The primary mission of this process is to reduce the inventory of unstable plutonium bearing sludge. The source of the sludge is residual and glovebox floor sweepings from the production of material at the Plutonium Finishing Plant (PFP). The reactive sludge is currently being stored in various gloveboxes at PFP. There are two types of the plutonium bearing material that will be thermally stabilized in the muffle furnace: Plutonium Reclamation Facility (PRF) sludge and Remote Mechanical C (RMC) Line material

  18. Stability and non-standard finite difference method of the generalized Chua's circuit

    KAUST Repository

    Radwan, Ahmed G.

    2011-08-01

    In this paper, we develop a framework to obtain approximate numerical solutions of the fractional-order Chua\\'s circuit with Memristor using a non-standard finite difference method. Chaotic response is obtained with fractional-order elements as well as integer-order elements. Stability analysis and the condition of oscillation for the integer-order system are discussed. In addition, the stability analyses for different fractional-order cases are investigated showing a great sensitivity to small order changes indicating the poles\\' locations inside the physical s-plane. The GrnwaldLetnikov method is used to approximate the fractional derivatives. Numerical results are presented graphically and reveal that the non-standard finite difference scheme is an effective and convenient method to solve fractional-order chaotic systems, and to validate their stability. © 2011 Elsevier Ltd. All rights reserved.

  19. Stability and response bounds of non-conservative linear systems

    DEFF Research Database (Denmark)

    Pommer, Christian

    2003-01-01

    For a linear system of second order differential equations the stability is studied by Lyapunov's direct method. The Lyapunov matrix equation is solved and a sufficient condition for stability is expressed by the system matrices. For a system which satisfies the condition for stability the Lyapunov...

  20. Relating the variation of secondary structure of gelatin at fish oil-water interface to adsorption kinetics, dynamic interfacial tension and emulsion stability.

    Science.gov (United States)

    Liu, Huihua; Wang, Bo; Barrow, Colin J; Adhikari, Benu

    2014-01-15

    The objectives of this study were to quantify the relationship between secondary structure of gelatin and its adsorption at the fish-oil/water interface and to quantify the implication of the adsorption on the dynamic interfacial tension (DST) and emulsion stability. The surface hydrophobicity of the gelatin solutions decreased when the pH increased from 4.0 to 6.0, while opposite tend was observed in the viscosity of the solution. The DST values decreased as the pH increased from 4.0 to 6.0, indicating that higher positive charges (measured trough zeta potential) in the gelatin solution tended to result in higher DST values. The adsorption kinetics of the gelatin solution was examined through the calculated diffusion coefficients (Deff). The addition of acid promoted the random coil and β-turn structures at the expense of α-helical structure. The addition of NaOH decreased the β-turn and increased the α-helix and random coil. The decrease in the random coil and triple helix structures in the gelatin solution resulted into increased Deff values. The highest diffusion coefficients, the highest emulsion stability and the lowest amount of random coil and triple helix structures were observed at pH=4.8. The lowest amount of random coil and triple helix structures in the interfacial protein layer correlated with the highest stability of the emulsion (highest ESI value). The lower amount of random coil and triple helix structures allowed higher coverage of the oil-water interface by relatively highly ordered secondary structure of gelatin. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Improving the clean-up efficiency of field soil contaminated with diesel oil by the application of stabilizers.

    Science.gov (United States)

    Chang, Yoon-Young; Roh, Hoon; Yang, Jae-Kyu

    2013-01-01

    Fenton-like oxidation in the presence of stabilizers has been applied in batch and column reactors to treat field soils contaminated with diesel oil. Citrates, ethylene diamine tetra-acetic acid (EDTA), ethylene diamine disuccinic acid (EDDS) and phosphates were assessed as stabilizers. The stability of hydrogen peroxide in the soil was evaluated by varying the concentration of each stabilizer and hydrogen peroxide. In a batch test, the residual concentration of hydrogen peroxide was shown to be directly related to the concentration of these stabilizers. Citrate showed the greatest stabilizing effect of the four stabilizers for hydrogen peroxide and 0.05 M was selected as the optimum dosage. In order to investigate the effect of stabilizer on the efficiency of removal of total petroleum hydrocarbons (TPH) in a column reactor, 30 mL of each stabilizer solution at pH 3 and containing 15% hydrogen peroxide was injected. The batch result confirmed that the greatest TPH removal took place in the presence of citrate in a column reactor. The order of TPH removal in the presence of stabilizers was: citrate > H3PO4 > EDDS > EDTA. TPH removal was affected by the concentration of stabilizer and the initial concentration of TPH. When 0.05 M citrate solution containing 15% hydrogen peroxide was applied to four field soils and an artificially contaminated soil, similar or better TPH removal was observed in the field soils compared to the artificially contaminated soil. This result suggests that Fenton-like oxidation with stabilizer can be effective in restoring field soils contaminated with diesel oil.

  2. Dispersal and metapopulation stability

    Directory of Open Access Journals (Sweden)

    Shaopeng Wang

    2015-10-01

    Full Text Available Metapopulation dynamics are jointly regulated by local and spatial factors. These factors may affect the dynamics of local populations and of the entire metapopulation differently. Previous studies have shown that dispersal can stabilize local populations; however, as dispersal also tends to increase spatial synchrony, its net effect on metapopulation stability has been controversial. Here we present a simple metapopulation model to study how dispersal, in interaction with other spatial and local processes, affects the temporal variability of metapopulations in a stochastic environment. Our results show that in homogeneous metapopulations, the local stabilizing and spatial synchronizing effects of dispersal cancel each other out, such that dispersal has no effect on metapopulation variability. This result is robust to moderate heterogeneities in local and spatial parameters. When local and spatial dynamics exhibit high heterogeneities, however, dispersal can either stabilize or destabilize metapopulation dynamics through various mechanisms. Our findings have important theoretical and practical implications. We show that dispersal functions as a form of spatial intraspecific mutualism in metapopulation dynamics and that its effect on metapopulation stability is opposite to that of interspecific competition on local community stability. Our results also suggest that conservation corridors should be designed with appreciation of spatial heterogeneities in population dynamics in order to maximize metapopulation stability.

  3. Moment stability for a predator-prey model with parametric dichotomous noises

    Science.gov (United States)

    Jin, Yan-Fei

    2015-06-01

    In this paper, we investigate the solution moment stability for a Harrison-type predator-prey model with parametric dichotomous noises. Using the Shapiro-Loginov formula, the equations for the first-order and second-order moments are obtained and the corresponding stable conditions are given. It is found that the solution moment stability depends on the noise intensity and correlation time of noise. The first-order and second-order moments become unstable with the decrease of correlation time. That is, the dichotomous noise can improve the solution moment stability with respect to Gaussian white noise. Finally, some numerical results are presented to verify the theoretical analyses. Project supported by the National Natural Science Foundation of China (Grant No. 11272051).

  4. Cyber Deterrence and Stability

    Energy Technology Data Exchange (ETDEWEB)

    Goychayev, Rustam [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Carr, Geoffrey A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Weise, Rachel A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Donnelly, David A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Clements, Samuel L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Benz, Jacob M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rodda, Kabrena E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bartholomew, Rachel A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McKinnon, Archibald D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Andres, Richard B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-09-30

    Throughout the 20th and early 21st centuries, deterrence and arms control have been cornerstones of strategic stability between the superpowers. However, the weaponization of the cyber realm by State actors and the multipolar nature of cyber conflict now undermines that stability. Strategic stability is the state in which nations believe that if they act aggressively to undermine U.S. national interests and the post-World War II liberal democratic order, the consequences will outweigh the benefits. The sense of lawlessness and lack of consequences in the cyber realm embolden States to be more aggressive in taking actions that undermine stability. Accordingly, this paper examines 1) the role of deterrence and arms control in securing cyber stability, and 2) the limitations and challenges associated with these traditional national security paradigms as applied to this emerging threat domain. This paper demonstrates that many 20th-century deterrence and arms control concepts are not particularly applicable in the cyber realm. However, they are not entirely irrelevant. The United States can distill lessons learned from this rich deterrence and arms control experience to develop and deploy a strategy to advance cyber stability.

  5. Generality of a congruity effect in judgements of relative order.

    Science.gov (United States)

    Liu, Yang S; Chan, Michelle; Caplan, Jeremy B

    2014-10-01

    The judgement of relative order (JOR) procedure is used to investigate serial-order memory. Measuring response times, the wording of the instructions (whether the earlier or the later item was designated as the target) reversed the direction of search in subspan lists (Chan, Ross, Earle, & Caplan Psychonomic Bulletin & Review, 16(5), 945-951, 2009). If a similar congruity effect applied to above-span lists and, furthermore, with error rate as the measure, this could suggest how to model order memory across scales. Participants performed JORs on lists of nouns (Experiment 1: list lengths = 4, 6, 8, 10) or consonants (Experiment 2: list lengths = 4, 8). In addition to the usual distance, primacy, and recency effects, instructions interacted with serial position of the later probe in both experiments, not only in response time, but also in error rate, suggesting that availability, not just accessibility, is affected by instructions. The congruity effect challenges current memory models. We fitted Hacker's (Journal of Experimental Psychology: Human Learning and Memory, 6(6), 651-675, 1980) self-terminating search model to our data and found that a switch in search direction could explain the congruity effect for short lists, but not longer lists. This suggests that JORs may need to be understood via direct-access models, adapted to produce a congruity effect, or a mix of mechanisms.

  6. Martensitic transformation, fcc and hcp relative phase stability, and thermal cycling effects in Fe-Mn and Fe-Mn-X Alloys (X = Si, Co)

    International Nuclear Information System (INIS)

    Baruj, Alberto

    1999-01-01

    In this Thesis we present a study of the fcc and hcp relative phase stability in the Fe-Mn and Fe-Mn-Co systems. In particular, we have investigated the effect of two main factors affecting the relative phase stability: changes in the chemical composition of the alloys and changes in the density of crystalline defects in the microstructure.In order to analyse the effect of chemical composition, we have performed an experimental study of the fcc/hcp martensitic transformation temperatures in Fe-Mn-Co alloys in the composition range lying between 15% and 34% Mn, and between 1% and 16% Co.We have measured the martensitic transformation temperatures by means of dilatometry and electrical resistivity.We have combined this information with measurements of the fcc/hcp martensitic transformation temperatures in Co-rich alloys to perform a modelling of the Gibbs energy function for the hcp phase in the Fe-Mn-Co and Fe-Co systems.We found that, for alloys in the Mn range between 17% and 25%, Co additions tend to stabilise slightly the fcc phase.In the alloys with Mn contents below that range, increasing the amount of Co stabilise the bcc phase. In alloys with Mn contents above 25% the Neel temperature is depressed by the addition of Co, which stabilise the hcp phase.In order to investigate the effect of changes in the density of crystalline defects, we have performed thermal cycling experiments through the fcc/hcp martensitic transformation in Fe-Mn, Fe-Mn-Co and Fe-Mn-Si alloys.We have applied the thermodynamic description obtained before in order to analyse these experiments.We found in the thermal cycling experiments a first stage where the martensitic transformation is promoted.This stage occurs in all the studied alloys during the first cycle or the two first cycles.Increasing the number of thermal cycles, the promotion stage is replaced by an inhibition of the transformation stage.We propose a possible microstructural interpretation of these phenomena where the plastic

  7. Developmental and Functional Expression of miRNA-Stability Related Genes in the Nervous System

    OpenAIRE

    de Sousa, ?rica; Walter, Lais Takata; Higa, Guilherme Shigueto Vilar; Casado, Ot?vio Augusto Nocera; Kihara, Alexandre Hiroaki

    2013-01-01

    In the nervous system, control of gene expression by microRNAs (miRNAs) has been investigated in fundamental processes, such as development and adaptation to ambient demands. The action of these short nucleotide sequences on specific genes depends on intracellular concentration, which in turn reflects the balance of biosynthesis and degradation. Whereas mechanisms underlying miRNA biogenesis has been investigated in recent studies, little is known about miRNA-stability related proteins. We fi...

  8. Lattice Boltzmann model for numerical relativity.

    Science.gov (United States)

    Ilseven, E; Mendoza, M

    2016-02-01

    In the Z4 formulation, Einstein equations are written as a set of flux conservative first-order hyperbolic equations that resemble fluid dynamics equations. Based on this formulation, we construct a lattice Boltzmann model for numerical relativity and validate it with well-established tests, also known as "apples with apples." Furthermore, we find that by increasing the relaxation time, we gain stability at the cost of losing accuracy, and by decreasing the lattice spacings while keeping a constant numerical diffusivity, the accuracy and stability of our simulations improve. Finally, in order to show the potential of our approach, a linear scaling law for parallelization with respect to number of CPU cores is demonstrated. Our model represents the first step in using lattice kinetic theory to solve gravitational problems.

  9. Single-shell tank interim stabilization project plan

    Energy Technology Data Exchange (ETDEWEB)

    Ross, W.E.

    1998-03-27

    Solid and liquid radioactive waste continues to be stored in 149 single-shell tanks at the Hanford Site. To date, 119 tanks have had most of the pumpable liquid removed by interim stabilization. Thirty tanks remain to be stabilized. One of these tanks (C-106) will be stabilized by retrieval of the tank contents. The remaining 29 tanks will be interim stabilized by saltwell pumping. In the summer of 1997, the US Department of Energy (DOE) placed a moratorium on the startup of additional saltwell pumping systems because of funding constraints and proposed modifications to the Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) milestones to the Washington State Department of Ecology (Ecology). In a letter dated February 10, 1998, Final Determination Pursuant to Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) in the Matter of the Disapproval of the DOE`s Change Control Form M-41-97-01 (Fitzsimmons 1998), Ecology disapproved the DOE Change Control Form M-41-97-01. In response, Fluor Daniel Hanford, Inc. (FDH) directed Lockheed Martin Hanford Corporation (LNMC) to initiate development of a project plan in a letter dated February 25, 1998, Direction for Development of an Aggressive Single-Shell Tank (SST) Interim Stabilization Completion Project Plan in Support of Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement). In a letter dated March 2, 1998, Request for an Aggressive Single-Shell Tank (SST) Interim Stabilization Completion Project Plan, the DOE reaffirmed the need for an aggressive SST interim stabilization completion project plan to support a finalized Tri-Party Agreement Milestone M-41 recovery plan. This project plan establishes the management framework for conduct of the TWRS Single-Shell Tank Interim Stabilization completion program. Specifically, this plan defines the mission needs and requirements; technical objectives and approach; organizational structure, roles, responsibilities

  10. Single-shell tank interim stabilization project plan

    International Nuclear Information System (INIS)

    Ross, W.E.

    1998-01-01

    Solid and liquid radioactive waste continues to be stored in 149 single-shell tanks at the Hanford Site. To date, 119 tanks have had most of the pumpable liquid removed by interim stabilization. Thirty tanks remain to be stabilized. One of these tanks (C-106) will be stabilized by retrieval of the tank contents. The remaining 29 tanks will be interim stabilized by saltwell pumping. In the summer of 1997, the US Department of Energy (DOE) placed a moratorium on the startup of additional saltwell pumping systems because of funding constraints and proposed modifications to the Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) milestones to the Washington State Department of Ecology (Ecology). In a letter dated February 10, 1998, Final Determination Pursuant to Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement) in the Matter of the Disapproval of the DOE's Change Control Form M-41-97-01 (Fitzsimmons 1998), Ecology disapproved the DOE Change Control Form M-41-97-01. In response, Fluor Daniel Hanford, Inc. (FDH) directed Lockheed Martin Hanford Corporation (LNMC) to initiate development of a project plan in a letter dated February 25, 1998, Direction for Development of an Aggressive Single-Shell Tank (SST) Interim Stabilization Completion Project Plan in Support of Hanford Federal Facility Agreement and Consent Order (Tri-Party Agreement). In a letter dated March 2, 1998, Request for an Aggressive Single-Shell Tank (SST) Interim Stabilization Completion Project Plan, the DOE reaffirmed the need for an aggressive SST interim stabilization completion project plan to support a finalized Tri-Party Agreement Milestone M-41 recovery plan. This project plan establishes the management framework for conduct of the TWRS Single-Shell Tank Interim Stabilization completion program. Specifically, this plan defines the mission needs and requirements; technical objectives and approach; organizational structure, roles, responsibilities

  11. Ordering transitions of weakly anisotropic hard rods in narrow slitlike pores.

    Science.gov (United States)

    Aliabadi, Roohollah; Gurin, Péter; Velasco, Enrique; Varga, Szabolcs

    2018-01-01

    The effect of strong confinement on the positional and orientational ordering is examined in a system of hard rectangular rods with length L and diameter D (L>D) using the Parsons-Lee modification of the second virial density-functional theory. The rods are nonmesogenic (L/Dlayers is allowed to form in the pore. In the extreme confinement limit of H≤2D, where only one-layer structures appear, we observe a structural transition from a planar to a homeotropic fluid layer with increasing density, which becomes sharper as L→H. In wider pores (2Dlayers, homeotropic order, and even combined bilayer structures (one layer is homeotropic, while the other is planar) can be stabilized at high densities. Moreover, first-order phase transitions can be seen between different structures. One of them emerges between a monolayer and a bilayer with planar orders at relatively low packing fractions.

  12. Phase stability in yttria-stabilized zirconia from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Carbogno, Christian; Scheffler, Matthias [Materials Department, University of California, Santa Barbara, CA (United States); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany); Levi, Carlos G.; Van de Walle, Chris G. [Materials Department, University of California, Santa Barbara, CA (United States)

    2012-07-01

    Zirconia based ceramics are of pivotal importance for a variety of industrial technologies, e.g., for thermal barrier coatings in gas and airplane turbines. Naturally, the stability of such coatings at elevated temperatures plays a critical role in these applications. It is well known that an aliovalent doping of tetragonal ZrO{sub 2} with yttria, which induces oxygen vacancies due to charge conservation, increases its thermodynamic stability. However, the atomistic mechanisms that determine the phase stability of such yttria-stabilized Zirconia (YSZ) coatings are not yet fully understood. In this work, we use density functional theory calculations to assess the electronic structure of the different YSZ polymorphs at various levels of doping. With the help of population analysis schemes, we are able to unravel the intrinsic mechanisms that govern the interaction in YSZ and that can so explain the relative stabilities of the various polymorphs. We critically compare our results to experimental measurements and discuss the implications of our findings with respect to other oxides.

  13. Molecular Packing and Arrangement Govern the Photo-Oxidative Stability of Organic Photovoltaic Materials

    KAUST Repository

    Mateker, William R.; Heumueller, Thomas; Cheacharoen, Rongrong; Sachs-Quintana, I. T.; Warnan, Julien; Liu, Xiaofeng; Bazan, Guillermo C.; Beaujuge, Pierre; McGehee, Michael D.

    2015-01-01

    For long-term performance chemically robust materials are desired for organic solar cells (OSCs). Illuminating neat films of OSC materials in air and tracking the rate of absorption loss, or photobleaching, can quickly screen a material’s photo-chemical stability. In this report, we photobleach neat films of OSC materials including polymers, solution-processed oligomers, solution-processed small molecules, and vacuum-deposited small molecules. Across the materials we test, we observe photobleaching rates that span seven orders of magnitude. Furthermore, we find that the film morphology of any particular material impacts the observed photobleaching rate, and that amorphous films photobleach faster than crystalline ones. In an extreme case, films of amorphous rubrene photobleach at a rate 2500 times faster than polycrystalline films. When we compare density to photobleaching rate, we find that stability increases with density. We also investigate the relationship between backbone planarity and chemical reactivity. The polymer PBDTTPD is more photostable than it’s more twisted and less ordered furan derivitative, PBDFTPD. Finally, we relate our work to what is known about the chemical stability of structural polymers, organic pigments, and organic light emitting diode materials. For the highest chemical stability, planar materials that form dense, crystalline film morphologies should be designed for OSCs.

  14. Molecular Packing and Arrangement Govern the Photo-Oxidative Stability of Organic Photovoltaic Materials

    KAUST Repository

    Mateker, William R.

    2015-08-19

    For long-term performance chemically robust materials are desired for organic solar cells (OSCs). Illuminating neat films of OSC materials in air and tracking the rate of absorption loss, or photobleaching, can quickly screen a material’s photo-chemical stability. In this report, we photobleach neat films of OSC materials including polymers, solution-processed oligomers, solution-processed small molecules, and vacuum-deposited small molecules. Across the materials we test, we observe photobleaching rates that span seven orders of magnitude. Furthermore, we find that the film morphology of any particular material impacts the observed photobleaching rate, and that amorphous films photobleach faster than crystalline ones. In an extreme case, films of amorphous rubrene photobleach at a rate 2500 times faster than polycrystalline films. When we compare density to photobleaching rate, we find that stability increases with density. We also investigate the relationship between backbone planarity and chemical reactivity. The polymer PBDTTPD is more photostable than it’s more twisted and less ordered furan derivitative, PBDFTPD. Finally, we relate our work to what is known about the chemical stability of structural polymers, organic pigments, and organic light emitting diode materials. For the highest chemical stability, planar materials that form dense, crystalline film morphologies should be designed for OSCs.

  15. A new reconfiguration scheme for voltage stability enhancement of radial distribution systems

    International Nuclear Information System (INIS)

    Arun, M.; Aravindhababu, P.

    2009-01-01

    Network reconfiguration is an operation problem, which entails altering the topological structure of the distribution feeders by rearranging the status of switches in order to obtain an optimal configuration in order to minimise the system losses. This paper presents a new reconfiguration algorithm that enhances voltage stability and improves the voltage profile besides minimising losses without incurring any additional cost for installation of capacitors, tap changing transformers and related switching equipment in the distribution system. Test results on a 69 node distribution system reveal the superiority of this algorithm.

  16. The adaptive synchronization of fractional-order Liu chaotic system ...

    Indian Academy of Sciences (India)

    In this paper, the chaos control and the synchronization of two fractional-order Liu chaotic systems with unknown parameters are studied. According to the Lyapunov stabilization theory and the adaptive control theorem, the adaptive control rule is obtained for the described error dynamic stabilization. Using the adaptive rule ...

  17. Stability-indicating UPLC method for determining related substances and degradants in dronedarone.

    Science.gov (United States)

    Pydimarry, Surya Prakash Rao; Cholleti, Vijay Kumar; Vangala, Ranga Reddy

    2014-08-01

    A simple, sensitive and reproducible method was developed on ultra-performance liquid chromatography coupled with photodiode array detection for the quantitative determination of dronedarone hydrochloride (DRO) in drug substance and pharmaceutical dosage forms. The method is applicable for the quantification of related substances and assays of drug substances. Chromatographic separation was achieved on Acquity UPLC BEH C8 100 mm, 2.1 mm and 1.7 µm columns, using gradient elution within a short run time of 10.0 min. The eluted compounds were monitored at 288 nm, the flow rate was 0.5 mL/min and the column oven temperature was maintained at 40°C. The resolution of DRO and 11 impurities (potentials and by-products) was greater than 2.0 for all pairs of components. The high correlation coefficient value (>0.9995) indicates the clear correlations between the concentrations of investigated compound and their peak areas within the test ranges. The repeatability and intermediate precision, expressed by the relative standard deviation, were less than 2.5%. The accuracy and validity of the method were further ascertained by performing recovery studies via a spike method. The accuracy of the method, expressed as relative error, was satisfactory. No interference was observed from concomitant substances normally added to the tablets. DRO was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. DRO was found to degrade significantly in acid and base stress conditions and to remain stable in thermal, photolytic degradation, oxidative and hydrolytic conditions. The degradation products were well resolved from primary peak and its impurities, proving that the method is stability indicating. The developed method was validated as per International Conference on Harmonization guidelines with respect to specificity, limit of detection, limit of quantification, linearity, accuracy, precision, solution stability and robustness

  18. Report order and identification of multidimensional stimuli: a study of event-related brain potentials.

    Science.gov (United States)

    Shieh, Kong-King; Shen, I-Hsuan

    2004-06-01

    An experiment was conducted to investigate the effect of order of report on multidimensional stimulus identification. Subjects were required to identify each two-dimensional symbol by pushing corresponding buttons on the keypad on which there were two columns representing the two dimensions. Order of report was manipulated for the dimension represented by the left or right column. Both behavioral data and event-related potentials were recorded from 14 college students. Behavioral data analysis showed that order of report had a significant effect on response times. Such results were consistent with those of previous studies. Analysis of event-related brain potentials showed significant differences in peak amplitude and mean amplitude at time windows of 120-250 msec. at Fz, F3, and F4 and of 350-750 msec. at Fz, F3, F4, Cz, and Pz. Data provided neurophysiological evidence that reporting dimensional values according to natural language habits was appropriate and less cognitively demanding.

  19. Butterworth passive filter in the fractional-order

    KAUST Repository

    Sołtan, Ahmed

    2011-12-01

    In this paper, the generalized analysis of the first Butterworth filter based on two passive elements is introduced in the fractional-order sense. The fractional-order condition of the Butterworth circuit is presented for the first time where it will lead us back to the known condition of the integer-order circuit when the two fractional-orders equal one. Therefore, the conventional behavior of the integer-order circuit is a narrow subset of the fractional-order ones. The circuit is studied under same and different order cases, and verified through their numerical simulations. Stability analysis is also introduced showing the poles location in the fractional-order versus integer order cases. © 2011 IEEE.

  20. Preservation of perceptual integration improves temporal stability of bimanual coordination in the elderly: an evidence of age-related brain plasticity.

    Science.gov (United States)

    Blais, Mélody; Martin, Elodie; Albaret, Jean-Michel; Tallet, Jessica

    2014-12-15

    Despite the apparent age-related decline in perceptual-motor performance, recent studies suggest that the elderly people can improve their reaction time when relevant sensory information are available. However, little is known about which sensory information may improve motor behaviour itself. Using a synchronization task, the present study investigates how visual and/or auditory stimulations could increase accuracy and stability of three bimanual coordination modes produced by elderly and young adults. Neurophysiological activations are recorded with ElectroEncephaloGraphy (EEG) to explore neural mechanisms underlying behavioural effects. Results reveal that the elderly stabilize all coordination modes when auditory or audio-visual stimulations are available, compared to visual stimulation alone. This suggests that auditory stimulations are sufficient to improve temporal stability of rhythmic coordination, even more in the elderly. This behavioural effect is primarily associated with increased attentional and sensorimotor-related neural activations in the elderly but similar perceptual-related activations in elderly and young adults. This suggests that, despite a degradation of attentional and sensorimotor neural processes, perceptual integration of auditory stimulations is preserved in the elderly. These results suggest that perceptual-related brain plasticity is, at least partially, conserved in normal aging. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. A non-linear reduced order methodology applicable to boiling water reactor stability analysis

    International Nuclear Information System (INIS)

    Prill, Dennis Paul

    2013-01-01

    Thermal-hydraulic coupling between power, flow rate and density, intensified by neutronics feedback are the main drivers of boiling water reactor (BWR) stability behavior. High-power low-flow conditions in connection with unfavorable power distributions can lead the BWR system into unstable regions where power oscillations can be triggered. This important threat to operational safety requires careful analysis for proper understanding. Analyzing an exhaustive parameter space of the non-linear BWR system becomes feasible with methodologies based on reduced order models (ROMs), saving computational cost and improving the physical understanding. Presently within reactor dynamics, no general and automatic prediction of high-dimensional ROMs based on detailed BWR models are available. In this thesis a systematic self-contained model order reduction (MOR) technique is derived which is applicable for several classes of dynamical problems, and in particular to BWRs of any degree of details. Expert knowledge can be given by operational, experimental or numerical transient data and is transfered into an optimal basis function representation. The methodology is mostly automated and provides the framework for the reduction of various different systems of any level of complexity. Only little effort is necessary to attain a reduced version within this self-written code which is based on coupling of sophisticated commercial software. The methodology reduces a complex system in a grid-free manner to a small system able to capture even non-linear dynamics. It is based on an optimal choice of basis functions given by the so-called proper orthogonal decomposition (POD). Required steps to achieve reliable and numerical stable ROM are given by a distinct calibration road-map. In validation and verification steps, a wide spectrum of representative test examples is systematically studied regarding a later BWR application. The first example is non-linear and has a dispersive character

  2. Stability of the high-order finite elements for acoustic or elastic wave propagation with high-order time stepping

    KAUST Repository

    De Basabe, Joná s D.; Sen, Mrinal K.

    2010-01-01

    popular in the recent past. We consider the Lax-Wendroff method (LWM) for time stepping and show that it allows for a larger time step than the classical leap-frog finite difference method, with higher-order accuracy. In particular the fourth-order LWM

  3. Dataset on the structure and thermodynamic and dynamic stability of Mo2ScAlC2 from experiments and first-principles calculations

    Directory of Open Access Journals (Sweden)

    Martin Dahlqvist

    2017-02-01

    Full Text Available The data presented in this paper are related to the research article entitled “Theoretical stability and materials synthesis of a chemically ordered MAX phase, Mo2ScAlC2, and its two-dimensional derivate Mo2ScC” (Meshkian et al. 2017 [1]. This paper describes theoretical phase stability calculations of the MAX phase alloy MoxSc3-xAlC2 (x=0, 1, 2, 3, including chemical disorder and out-of-plane order of Mo and Sc along with related phonon dispersion and Bader charges, and Rietveld refinement of Mo2ScAlC2. The data is made publicly available to enable critical or extended analyzes.

  4. Relation between stability and resilience determines the performance of early warning signals under different environmental drivers.

    Science.gov (United States)

    Dai, Lei; Korolev, Kirill S; Gore, Jeff

    2015-08-11

    Shifting patterns of temporal fluctuations have been found to signal critical transitions in a variety of systems, from ecological communities to human physiology. However, failure of these early warning signals in some systems calls for a better understanding of their limitations. In particular, little is known about the generality of early warning signals in different deteriorating environments. In this study, we characterized how multiple environmental drivers influence the dynamics of laboratory yeast populations, which was previously shown to display alternative stable states [Dai et al., Science, 2012]. We observed that both the coefficient of variation and autocorrelation increased before population collapse in two slowly deteriorating environments, one with a rising death rate and the other one with decreasing nutrient availability. We compared the performance of early warning signals across multiple environments as "indicators for loss of resilience." We find that the varying performance is determined by how a system responds to changes in a specific driver, which can be captured by a relation between stability (recovery rate) and resilience (size of the basin of attraction). Furthermore, we demonstrate that the positive correlation between stability and resilience, as the essential assumption of indicators based on critical slowing down, can break down in this system when multiple environmental drivers are changed simultaneously. Our results suggest that the stability-resilience relation needs to be better understood for the application of early warning signals in different scenarios.

  5. Magnetohydrodynamic stability of tokamaks

    CERN Document Server

    Zohm, Hartmut

    2014-01-01

    This book bridges the gap between general plasma physics lectures and the real world problems in MHD stability. In order to support the understanding of concepts and their implication, it refers to real world problems such as toroidal mode coupling or nonlinear evolution in a conceptual and phenomenological approach. Detailed mathematical treatment will involve classical linear stability analysis and an outline of more recent concepts such as the ballooning formalism. The book is based on lectures that the author has given to Master and PhD students in Fusion Plasma Physics. Due its strong lin

  6. Analysis of stability parameters in relation to precipitation associated

    Indian Academy of Sciences (India)

    Atmospheric instability; stability indices; Richardson number; vertical wind ... is used to compute some important dynamic/thermodynamic parameters and are ... (i*) well indicate the occurrence of thunderstorms about 2 hours in advance.

  7. Triphenylamine - a 'new' stabilizer for nitrocellulose based propellants. Pt. 1: chemical stability studies

    Energy Technology Data Exchange (ETDEWEB)

    Wilker, Stephan; Heeb, Gerhard [WIWEB ASt Heimerzheim, Grosses Cent, 53913 Swisttal (Germany); Vogelsanger, Beat [Nitrochemie Wimmis AG, Niesenstr. 44, 3752 Wimmis (Switzerland); Petrzilek, Jan; Skladal, Jan [Explosia a.s. - Research Institute of Industrial Chemistry (VUPCH), 532 17 Pardubice (Czech Republic)

    2007-04-15

    Triphenylamine (TPA) was used for the first time in France in 1937 as a stabilizer for propellants. The stability of those samples was described as 'good'. Around 1950 an American group produced TPA stabilized propellants and investigated the decomposition mechanism. Apart from one single experiment in the 1970s no further attempts were made to take TPA as a stabilizer for propellants. With the background of an increasingly critical discussion about nitrosamines in propellants and their declaration of being carcinogenic, TPA revealed a renaissance since the year 2000. To achieve the goal of nitrosamine free propellants several TPA stabilized propellants were produced. Their processability, stability and ballistic properties were investigated. This publication summarizes the most important results of stability tests on more than 30 different TPA stabilized propellants including the decomposition mechanism, the synthesis of the consecutive products and their stabilizing properties. In addition, the internal compatibility of TPA with the most important propellant ingredients is discussed and its relative decomposition rate is compared with that of other stabilizers. In summary TPA is a suitable stabilizer for propellants. It has nevertheless two disadvantages. It is relatively rapidly consumed in double base formulations (which makes it difficult to pass the criteria of AOP-48, Ed. 2) and the stabilizing activity of the two major consecutive products 4-NO{sub 2}-TPA and especially 4,4{sup '}-di-NO{sub 2}-TPA is low. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  8. Analysis of stability parameters in relation to precipitation associated ...

    Indian Academy of Sciences (India)

    erty and crops; human and animal fatalities, and also aviation hazards. ... Keywords. Atmospheric instability; stability indices; Richardson number; vertical wind shear; energy-helicity index; ... ing the genesis and development of severe weather.

  9. Multi-bi- and tri-stability using nonlinear plasmonic Fano resonators

    KAUST Repository

    Amin, Muhammad

    2013-09-01

    A plasmonic Fano resonator embedding Kerr nonlinearity is used to achieve multi-bi- and tri-stability. Fano resonance is obtained by inducing higher-order plasmon modes on metallic surfaces via geometrical symmetry breaking. The presence of the multiple higher order plasmon modes provides the means for producing multi-bi- or tri-stability in the response of the resonator when it is loaded with a material with Kerr nonlinearity. The multi-stability in the response of the proposed resonator enables its use in three-state all optical memory and switching applications. © 2013 IEEE.

  10. Explicit strong stability preserving multistep Runge–Kutta methods

    KAUST Repository

    Bresten, Christopher; Gottlieb, Sigal; Grant, Zachary; Higgs, Daniel; Ketcheson, David I.; Né meth, Adrian

    2015-01-01

    High-order spatial discretizations of hyperbolic PDEs are often designed to have strong stability properties, such as monotonicity. We study explicit multistep Runge-Kutta strong stability preserving (SSP) time integration methods for use with such discretizations. We prove an upper bound on the SSP coefficient of explicit multistep Runge-Kutta methods of order two and above. Numerical optimization is used to find optimized explicit methods of up to five steps, eight stages, and tenth order. These methods are tested on the linear advection and nonlinear Buckley-Leverett equations, and the results for the observed total variation diminishing and/or positivity preserving time-step are presented.

  11. Explicit strong stability preserving multistep Runge–Kutta methods

    KAUST Repository

    Bresten, Christopher

    2015-10-15

    High-order spatial discretizations of hyperbolic PDEs are often designed to have strong stability properties, such as monotonicity. We study explicit multistep Runge-Kutta strong stability preserving (SSP) time integration methods for use with such discretizations. We prove an upper bound on the SSP coefficient of explicit multistep Runge-Kutta methods of order two and above. Numerical optimization is used to find optimized explicit methods of up to five steps, eight stages, and tenth order. These methods are tested on the linear advection and nonlinear Buckley-Leverett equations, and the results for the observed total variation diminishing and/or positivity preserving time-step are presented.

  12. Positive polynomials and robust stabilization with fixed-order controllers

    Czech Academy of Sciences Publication Activity Database

    Henrion, Didier; Šebek, M.; Kučera, V.

    2003-01-01

    Roč. 48, č. 7 (2003), s. 1178-1186 ISSN 0018-9286 R&D Projects: GA ČR GA102/02/0709; GA MŠk ME 496 Institutional research plan: CEZ:AV0Z1075907 Keywords : fixed-order control lers * linear matrix inequality * polynomials, robust control Subject RIV: BC - Control Systems Theory Impact factor: 1.896, year: 2003

  13. Modulation stability and optical soliton solutions of nonlinear Schrödinger equation with higher order dispersion and nonlinear terms and its applications

    Science.gov (United States)

    Arshad, Muhammad; Seadawy, Aly R.; Lu, Dianchen

    2017-12-01

    In optical fibers, the higher order non-linear Schrödinger equation (NLSE) with cubic quintic nonlinearity describes the propagation of extremely short pulses. We constructed bright and dark solitons, solitary wave and periodic solitary wave solutions of generalized higher order NLSE in cubic quintic non Kerr medium by applying proposed modified extended mapping method. These obtained solutions have key applications in physics and mathematics. Moreover, we have also presented the formation conditions on solitary wave parameters in which dark and bright solitons can exist for this media. We also gave graphically the movement of constructed solitary wave and soliton solutions, that helps to realize the physical phenomena's of this model. The stability of the model in normal dispersion and anomalous regime is discussed by using the modulation instability analysis, which confirms that all constructed solutions are exact and stable. Many other such types of models arising in applied sciences can also be solved by this reliable, powerful and effective method.

  14. Phase stabilities at a glance: Stability diagrams of nickel dipnictides

    International Nuclear Information System (INIS)

    Bachhuber, F.; Rothballer, J.; Weihrich, R.; Söhnel, T.

    2013-01-01

    In the course of the recent advances in chemical structure prediction, a straightforward type of diagram to evaluate phase stabilities is presented based on an expedient example. Crystal structures and energetic stabilities of dipnictides NiPn 2 (Pn = N, P, As, Sb, Bi) are systematically investigated by first principles calculations within the framework of density functional theory using the generalized gradient approximation to treat exchange and correlation. These dipnictides show remarkable polymorphism that is not yet understood systematically and offers room for the discovery of new phases. Relationships between the concerned structures including the marcasite, the pyrite, the arsenopyrite/CoSb 2 , and the NiAs 2 types are highlighted by means of common structural fragments. Electronic stabilities of experimentally known and related AB 2 structure types are presented graphically in so-called stability diagrams. Additionally, competing binary phases are taken into consideration in the diagrams to evaluate the stabilities of the title compounds with respect to decomposition. The main purpose of the stability diagrams is the introduction of an image that enables the estimation of phase stabilities at a single glance. Beyond that, some of the energetically favored structure types can be identified as potential new phases

  15. Stability of digital feedback control systems

    Directory of Open Access Journals (Sweden)

    Larkin Eugene

    2018-01-01

    Lag time characteristics are used for investigation of stability of linear systems. Digital PID controller is divided onto linear part, which is realized with a soft and pure lag unit, which is realized with both hardware and software. With use notions amplitude and phase margins, condition for stability of system functioning are obtained. Theoretical results are confirm with computer experiment carried out on the third-order system.

  16. Stability and degradation mechanisms in organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ecker, Bernhard

    2012-04-26

    This thesis deals with stability improvements and the investigation of degradation mechanisms in organic solar cells. Organic solar cells have been in the focus of extensive academic research for over almost two decades and are currently entering the market in small scale applications. For successful large scale applications, next to the improvement of the power conversion efficiency, the stability of organic solar cells has to be increased. This thesis is dedicated to the investigation of novel materials and architectures to study stability-related issues and degradation mechanisms in order to contribute to the basic understanding of the working principles of organic solar cells. Here, impedance spectroscopy, a frequency domain technique, is used to gain information about stability and degradation mechanisms in organic solar cells. In combination with systematic variations in the preparation of solar cells, impedance spectroscopy gives the possibility to differentiate between interface and bulk dominated effects. Additionally, impedance spectroscopy gives access to the dielectric properties of the device, such as capacitance. This offers among other things the opportunity to probe the charge carrier concentration and the density of states. Another powerful way of evaluation is the combination of experimentally obtained impedance spectra with equivalent circuit modelling. The thesis presents results on novel materials and solar cell architectures for efficient hole and electron extraction. This indicates the importance of knowledge over interlayers and interfaces for improving both the efficiency and stability of organic solar cells.

  17. Globalization by the Souths. Chinese-African Relations and International Order

    Directory of Open Access Journals (Sweden)

    Julien Rajaoson

    2014-11-01

    Full Text Available This study focuses on worldwide governance. It will be related to the Assian approach of international relationships. This approach claiming by the Chinese is closed to the David Miller Nationalist and liberal way of thinking. But it remains very restrictive because it is only based on the liberal economic point of view. We will do a critical study of the principles which are regulating the governances and we will analyse a special sectorial field: the Sino-African relations. These thoughts and statements need to have a sectorial dimension of approaching matters. The management of the different governments can have effects on local realities of people's life and on investments. In thirty years China passed from an emerging country to the second worldwide economically powerful country just behind the United States. Now, they must have an interdependance relationship with the United States. It is very important and necessary to undermine this interdependance relationship in order to understand how its economic strategy has an influence upon the worldwide market. And from this study, we will understand how the Chinese relate to the balance of power they are dealing with.

  18. Self-Referential Processing in Adolescents: Stability of Behavioral and Event-Related Potential Markers

    Science.gov (United States)

    Auerbach, Randy P.; Bondy, Erin; Stanton, Colin H.; Webb, Christian A.; Shankman, Stewart A.; Pizzagalli, Diego A.

    2016-01-01

    The self-referential encoding task (SRET)—an implicit measure of self-schema—has been used widely to probe cognitive biases associated with depression, including among adolescents. However, research testing the stability of behavioral and electrocortical effects is sparse. Therefore, the current study sought to evaluate the stability of behavioral markers and event-related potentials (ERP) elicited from the SRET over time in healthy, female adolescents (n = 31). At baseline, participants were administered a diagnostic interview and a self-report measure of depression severity. In addition, they completed the SRET while 128-channel event-related potential (ERP) data were recorded to examine early (P1) and late (late positive potential [LPP]) ERPs. Three months later, participants were re-administered the depression self-report measure and the SRET in conjunction with ERPs. Results revealed that healthy adolescents endorsed, recalled, and recognized more positive and fewer negative words at each assessment, and these effects were stable over time (rs = 0.44–0.83). Similarly, they reported a faster reaction time when endorsing self-relevant positive words, as opposed to negative words, at both the initial and follow-up assessment (r = 0.82). Second, ERP responses, specifically potentiated P1 and late LPP positivity to positive versus negative words, were consistent over time (rs = 0.56–0.83), and the internal reliability of ERPs were robust at each time point (rs = 0.52–0.80). As a whole, these medium-to-large effects suggest that the SRET is a reliable behavioral and neural probe of self-referential processing. PMID:27302282

  19. Robust Control for Microgravity Vibration Isolation using Fixed Order, Mixed H2/Mu Design

    Science.gov (United States)

    Whorton, Mark

    2003-01-01

    Many space-science experiments need an active isolation system to provide a sufficiently quiescent microgravity environment. Modern control methods provide the potential for both high-performance and robust stability in the presence of parametric uncertainties that are characteristic of microgravity vibration isolation systems. While H2 and H(infinity) methods are well established, neither provides the levels of attenuation performance and robust stability in a compensator with low order. Mixed H2/H(infinity), controllers provide a means for maximizing robust stability for a given level of mean-square nominal performance while directly optimizing for controller order constraints. This paper demonstrates the benefit of mixed norm design from the perspective of robustness to parametric uncertainties and controller order for microgravity vibration isolation. A nominal performance metric analogous to the mu measure, for robust stability assessment is also introduced in order to define an acceptable trade space from which different control methodologies can be compared.

  20. The Development of Perceptual Sensitivity to Second-Order Facial Relations in Children

    Science.gov (United States)

    Baudouin, Jean-Yves; Gallay, Mathieu; Durand, Karine; Robichon, Fabrice

    2010-01-01

    This study investigated children's perceptual ability to process second-order facial relations. In total, 78 children in three age groups (7, 9, and 11 years) and 28 adults were asked to say whether the eyes were the same distance apart in two side-by-side faces. The two faces were similar on all points except the space between the eyes, which was…

  1. MHD stability analysis using higher order spline functions

    Energy Technology Data Exchange (ETDEWEB)

    Ida, Akihiro [Department of Energy Engineering and Science, Graduate School of Engineering, Nagoya University, Nagoya, Aichi (Japan); Todoroki, Jiro; Sanuki, Heiji

    1999-04-01

    The eigenvalue problem of the linearized magnetohydrodynamic (MHD) equation is formulated by using higher order spline functions as the base functions of Ritz-Galerkin approximation. When the displacement vector normal to the magnetic surface (in the magnetic surface) is interpolated by B-spline functions of degree p{sub 1} (degree p{sub 2}), which is continuously c{sub 1}-th (c{sub 2}-th) differentiable on neighboring finite elements, the sufficient conditions for the good approximation is given by p{sub 1}{>=}p{sub 2}+1, c{sub 1}{<=}c{sub 2}+1, (c{sub 1}{>=}1, p{sub 2}{>=}c{sub 2}{>=}0). The influence of the numerical integration upon the convergence of calculated eigenvalues is discussed. (author)

  2. FINANCIAL STABILITY OF ISLAMIC AND CONVENTIONAL BANKS IN BANGLADESH: REVISITING STABILITY MEASURES AND ANALYZING STABILITY BEHAVIOR

    Directory of Open Access Journals (Sweden)

    Md Enayet Hossain

    2018-03-01

    Full Text Available This study intends to assess the relative financial stability of Islamic banks in Bangladesh using three different Z-Scores as financial stability measures, based on a sample of 29 listed commercial banks (23 conventional and 6 Islamic in Bangladesh over the period 2005-2016. Apart from the existing measure of financial stability, Z-Score, the paper contributes to the literature by developing an alternative Z-Score based on bank’s loan portfolio infection ratio. We first use pair-wise comparison and find that Islamic banks are financially more stable in two stability measures i.e. Z-Score (based on Capital Adequacy Ratio and Z-Score (based on Infection Ratio. We then perform static (random effects and dynamic (GMM panel data analysis. By controlling for bank-specific, industry-specific and macroeconomic variables in the regressions, we find that Islamic banks are financially more stable in 2 panel regressions of Z-Score (based on Infection Ratio. We also find that the presence of Islamic banks increases the stability of all banks in the system including their conventional peers.

  3. Reduced Order Modeling in General Relativity

    Science.gov (United States)

    Tiglio, Manuel

    2014-03-01

    Reduced Order Modeling is an emerging yet fast developing filed in gravitational wave physics. The main goals are to enable fast modeling and parameter estimation of any detected signal, along with rapid matched filtering detecting. I will focus on the first two. Some accomplishments include being able to replace, with essentially no lost of physical accuracy, the original models with surrogate ones (which are not effective ones, that is, they do not simplify the physics but go on a very different track, exploiting the particulars of the waveform family under consideration and state of the art dimensional reduction techniques) which are very fast to evaluate. For example, for EOB models they are at least around 3 orders of magnitude faster than solving the original equations, with physically equivalent results. For numerical simulations the speedup is at least 11 orders of magnitude. For parameter estimation our current numbers are about bringing ~100 days for a single SPA inspiral binary neutron star Bayesian parameter estimation analysis to under a day. More recently, it has been shown that the full precessing problem for, say, 200 cycles, can be represented, through some new ideas, by a remarkably compact set of carefully chosen reduced basis waveforms (~10-100, depending on the accuracy requirements). I will highlight what I personally believe are the challenges to face next in this subarea of GW physics and where efforts should be directed. This talk will summarize work in collaboration with: Harbir Antil (GMU), Jonathan Blackman (Caltech), Priscila Canizares (IoA, Cambridge, UK), Sarah Caudill (UWM), Jonathan Gair (IoA. Cambridge. UK), Scott Field (UMD), Chad R. Galley (Caltech), Frank Herrmann (Germany), Han Hestahven (EPFL, Switzerland), Jason Kaye (Brown, Stanford & Courant). Evan Ochsner (UWM), Ricardo Nochetto (UMD), Vivien Raymond (LIGO, Caltech), Rory Smith (LIGO, Caltech) Bela Ssilagyi (Caltech) and MT (UMD & Caltech).

  4. Slow VO₂ kinetics during moderate-intensity exercise as markers of lower metabolic stability and lower exercise tolerance.

    Science.gov (United States)

    Grassi, Bruno; Porcelli, Simone; Salvadego, Desy; Zoladz, Jerzy A

    2011-03-01

    An analysis of previously published data obtained by our group on patients characterized by markedly slower pulmonary VO₂ kinetics (heart transplant recipients, patients with mitochondrial myopathies, patients with McArdle disease) was carried out in order to suggest that slow VO₂ kinetics should not be considered the direct cause, but rather a marker, of impaired exercise tolerance. For a given ATP turnover rate, faster (or slower) VO₂ kinetics are associated with smaller (or greater) muscle [PCr] decreases. The latter, however, should not be taken per se responsible for the higher (or lower) exercise tolerance, but should be considered within the general concept of "metabolic stability". Good muscle metabolic stability at a given ATP turnover rate (~power output) is associated with relatively smaller decreases, compared to rest, in [PCr] and in the Gibbs free energy of ATP hydrolysis, as well as with relatively smaller increases in [Pi], [ADP(free)], [AMP(free)], and [IMP(free)], metabolites directly related to fatigue. Disturbances in muscle metabolic stability can affect muscle function in various ways, whereas good metabolic stability is associated with less fatigue and higher exercise tolerance. Smaller [PCr] decreases, however, are strictly associated with a faster VO₂ kinetics. Thus, faster VO₂ kinetics may simply be an "epiphenomenon" of a relatively higher metabolic stability, which would then represent the relevant variable in terms of fatigue and exercise tolerance.

  5. Relative stiffness of 3 bandage/splint constructs for stabilization of equine midmetacarpal fractures.

    Science.gov (United States)

    Lutter, John D; Cary, Julie A; Stephens, Robert R; Potts, Logan B

    2015-01-01

    Determine the relative stiffness of 3 bandage/splint constructs intended for emergency fracture stabilization. Experimental model. A single plane free end deflection model was developed to simulate the forces placed on a bandage/splint construct during stabilization of a complete mid-metacarpal bone fracture. The total deflection of the model in one plane was measured following application of 3 different bandage/splint combinations including a classic, 3 layered Robert Jones Bandage (RJB) with a splint placed on the outside of the bandage (RJB-3), an RJB with splint placed after the first of 3 bandage layers (RJB-1), and a single layer full limb bandage with external splint (SS). Comparisons were made between the deflections of the model with each bandage/splint combinations in an effort to determine the most effective method for field fracture stabilization. Laboratory. No animals were utilized in data collection for this study. Two live horses were utilized during the pilot study. Application of bandage and splint to a model intended to simulate the bending force on a lower forelimb fracture in a horse Deflection was determined by the difference between the height of the model's supported free end before application of a 4.5 kg weight and at the conclusion of the deflection test. There was no significant difference in the amount of deflection between bandage/splint combinations (78 ± 32 mm (RJB-1), 94 ± 44 mm (RJB-3), and 93 ± 33 mm (SS)) CONCLUSIONS: The one-layer bandage with splint was equivalent to either RJB configuration in the mean amount of deflection in the simple model of a fracture. © Veterinary Emergency and Critical Care Society 2015.

  6. Stability of concentration-related self-interstitial atoms in fusion material tungsten

    Science.gov (United States)

    Hong, Zhang; Shu-Long, Wen; Min, Pan; Zheng, Huang; Yong, Zhao; Xiang, Liu; Ji-Ming, Chen

    2016-05-01

    Based on the density functional theory, we calculated the structures of the two main possible self-interstitial atoms (SIAs) as well as the migration energy of tungsten (W) atoms. It was found that the difference of the and formation energies is 0.05-0.3 eV. Further analysis indicated that the stability of SIAs is closely related to the concentration of the defect. When the concentration of the point defect is high, SIAs are more likely to exist, SIAs are the opposite. In addition, the vacancy migration probability and self-recovery zones for these SIAs were researched by making a detailed comparison. The calculation provided a new viewpoint about the stability of point defects for self-interstitial configurations and would benefit the understanding of the control mechanism of defect behavior for this novel fusion material. Project supported by the Fundamental Research Funds for the Central Universities of Ministry of Education of China (Grant Nos. A0920502051411-5 and 2682014ZT30), the Program of International Science and Technology Cooperation, China (Grant No. 2013DFA51050), the National Magnetic Confinement Fusion Science Program, China (Grant Nos. 2011GB112001 and 2013GB110001), the National High Technology Research and Development Program of China (Grant No. 2014AA032701), the National Natural Science Foundation of China (Grant No. 11405138), the Southwestern Institute of Physics Funds, China, the Western Superconducting Technologies Company Limited, China, the Qingmiao Plan of Southwest Jiaotong University, China (Grant No. A0920502051517-6), and the China Postdoctoral Science Foundation (Grant No. 2014M560813).

  7. Colloidal Stability of Gold Nanoparticles Coated with Multithiol-Poly(ethylene glycol) Ligands: Importance of Structural Constraints of the Sulfur Anchoring Groups

    Science.gov (United States)

    2013-08-13

    order: monothiol < flexible dithiol < constrained dithiol < disulfide. The present study indicates that the colloidal stability of thiolated ligand...protein/ polymer - negatively charged AuNP) and hydrophobic adsorption (hydrophobic protein pockets - AuNP).1, 20 Each mechanism will also be...colloidal stability has been significantly improved by preparing a relatively thicker shell with polymers or polyelectrolytes such as poly(N-vinyl-2

  8. Axisymmetric stability of vertically asymmetric tokamaks at large beta poloidal

    International Nuclear Information System (INIS)

    Yamazaki, K.; Fishman, H.; Okabayashi, M.; Todd, A.M.M.

    1981-09-01

    The stability of high-β vertically asymmetric tokamak equilibria to rigid displacements is investigated analytically. It is found that vertical stability at large beta poloidal is mainly determined by a coupling between the shape of the plasma surface and the Shafranov shift of the magnetic axis. To the lowest order, symmetric components of the plasma surface shape are found to be the critical destabilizing elements. Asymmetric components have little effect. The inclusion of higher order terms in the high β tokamak expansion leads to further destabilization. Qualitative agreement between these analytic results and numerical stability calculations using the PEST code is demonstrated

  9. Experimental and theoretical studies on stability of new stabilizers for N-methyl-P-nitroaniline derivative in CMDB propellants

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Qiufan [Xi’an Modern Chemistry Research Institute, Xi’an 710065 (China); Fan, Xuezhong, E-mail: xuezhongfan@126.com [Xi’an Modern Chemistry Research Institute, Xi’an 710065 (China); Li, Jizhen [Xi’an Modern Chemistry Research Institute, Xi’an 710065 (China); Key Laboratory of Applied Surface and Colloid Chemistry, MOE/School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062 (China); Bi, Fuqiang; Fu, Xiaolong; Zhai, Lianjie [Xi’an Modern Chemistry Research Institute, Xi’an 710065 (China)

    2017-04-05

    Highlights: • Five new stabilizers have been designed and synthesized. • The influence of the carbon chain length on the stability of propellants was studied. • Effects of temperature on the reactions of stabilizers and nitrogen oxides were explained. • The new stabilizer n-BNA was one of the most promising stabilizers. - Abstract: Although N-methyl-P-nitroaniline (MNA) was a quite effective stabilizer in composite modified double base (CMDB) propellants, it undergoes crystallization easily from nitroglycerin (NG) during storage. In order to improve its solubility in nitroglycerin (NG) and the stability in propellants, several new stabilizers including N-ethyl-p-nitroaniline (ENA), N-n-propyl-p-nitroaniline (n-PNA), N-i-propyl-p-nitroaniline (i-PNA), N-n-butyl-p-nitroaniline (n-BNA) and N-t-butyl-p-nitroaniline (t-BNA) were designed and synthesized to replace MNA by increasing the carbon chain length. The interaction between NG and different stabilizers was simulation by Materials Studio 5.5 and the stability and the high temperature stability performance of those new stabilizers in propellants were calculated by Gaussian 09. It was found that both the solubility of new stabilizers in NG and the stability and the high temperature stability performance of those in propellants were improved when the carbon chain length of substitution groups on nitrogen atom was increased. Thus, the n-BNA was a most potential stabilizer. Then all properties of the stabilizers were studied experimentally, which was agreement well with the theoretical analysis.

  10. Time-discrete higher order ALE formulations: a priori error analysis

    KAUST Repository

    Bonito, Andrea

    2013-03-16

    We derive optimal a priori error estimates for discontinuous Galerkin (dG) time discrete schemes of any order applied to an advection-diffusion model defined on moving domains and written in the Arbitrary Lagrangian Eulerian (ALE) framework. Our estimates hold without any restrictions on the time steps for dG with exact integration or Reynolds\\' quadrature. They involve a mild restriction on the time steps for the practical Runge-Kutta-Radau methods of any order. The key ingredients are the stability results shown earlier in Bonito et al. (Time-discrete higher order ALE formulations: stability, 2013) along with a novel ALE projection. Numerical experiments illustrate and complement our theoretical results. © 2013 Springer-Verlag Berlin Heidelberg.

  11. Fractional Differential Equations in Terms of Comparison Results and Lyapunov Stability with Initial Time Difference

    Directory of Open Access Journals (Sweden)

    Coşkun Yakar

    2010-01-01

    Full Text Available The qualitative behavior of a perturbed fractional-order differential equation with Caputo's derivative that differs in initial position and initial time with respect to the unperturbed fractional-order differential equation with Caputo's derivative has been investigated. We compare the classical notion of stability to the notion of initial time difference stability for fractional-order differential equations in Caputo's sense. We present a comparison result which again gives the null solution a central role in the comparison fractional-order differential equation when establishing initial time difference stability of the perturbed fractional-order differential equation with respect to the unperturbed fractional-order differential equation.

  12. Long-term process of reforming the economy of Republic of Serbia in order to achieve macroeconomic stabilization: From transient changes to the activist approach

    Directory of Open Access Journals (Sweden)

    Gavrilović Milica

    2015-01-01

    Full Text Available In today's economy, which is burdened by problems such as non-productive economy, high unemployment rates, constant inflationary pressures, great attention is paid to the interaction of monetary and fiscal policies in order to achieve macroeconomic stability. There is no universal model of economic policy even in countries around the world, nor in the Serbian economy, and policy makers are looking for the optimal design of monetary and fiscal strategies and their synchronization with other non-negligible specific economic policy objectives (in terms of balance of payments, objectives related to foreign currency course, the distribution of income, implemented stage of market reforms of the nineties, and then phase of reforms in the first decade of the 21st century. How good coordination of monetary and fiscal measures can be no qualitative basis, or as it is not possible to reconstruct and degrade previous economic structure, and that there is no definition of the new strategy, and continued the process of reforming and in the period from the time of deepening global financial crisis in 2008 . The Republic of Serbia, a country whose economy in the long process of reforming, seeks better use of comparative advantages, encouraging production and employment, adequate planning and allocation of available resources of its own and charge, absorption of new technologies, intensifying exports, encouraging investment, and with a constant potential danger which increase the vulnerability of small economies. The solid foundations of macroeconomic stability and discipline must be in production, proper allocation of resources, which will run the economy, and then increase the employment rate, and therefore national income. of crucial importance of good projections of macroeconomic aggregates, because of them depend on public revenue and public expenditure.

  13. Enhancement of stability of various nZVI suspensions used in groundwater remediation with environmentally friendly organic stabilizers

    Science.gov (United States)

    Schmid, Doris; Wagner, Stephan; Velimirović, Milica; Laumann, Susanne; Micić, Vesna; Hofmann, Thilo

    2014-05-01

    The use of nanoscale zero-valent iron (nZVI) particles for in situ remediation of polluted soil and groundwater has been shown as one of the most promising techniques [1]. The success of this technology depends on the mobility, reactivity, and longevity of nZVI particles. The mobility of nZVI particles depends on the properties of the single particles, stability of the particle suspension, and the aquifer material [1,2]. In order to enhance the mobility of nZVI, the mobility-decisive properties of the nZVI particles in suspension such as concentration, size distribution, surface charge, and sedimentation rate have to be investigated and optimized. Previous studies showed that pristine nZVI particles aggregate rapidly in water, reducing the particles radius of influence after injection [3]. In order to prevent aggregation and sedimentation of the nZVI particles, and consequently improve the stability of nZVI suspension and therefore the mobility of the nZVI particles, surface stabilizers can be used to provide electrostatic repulsion and steric or electrosteric stabilization [3,4]. The objective of this lab-scale study is to investigate the potential for enhancing the stability of different nZVI suspensions by means of environmentally friendly organic stabilizers, including carboxymethyl cellulose, pectin, alginate, xanthan, and guar gum. The different nZVI particles used included pristine and polyacrylic acid-coated nZVI particles provided in suspension (Nanofer 25 and Nanofer 25S, respectively, NANOIRON s.r.o., Czech Republic), air-stable nZVI particles (Nanofer Star, (NANOIRON s.r.o., Czech Republic), and milled iron flakes (UVR-FIA, Germany). In order to study the enhancement of nZVI stability (1 g L-1 total iron) different concentrations of organic stabilizers (1-20 wt.%) were applied in these nZVI suspensions. Each nZVI suspension was freshly prepared and treated for 10 minutes with Ultra-Turrax (15 000 rpm) and 10 minutes ultrasonic bath prior to

  14. The effect of hydroxyl groups on the stability and thermodynamic properties of polyhydroxylated xanthones as calculated by density functional theory

    International Nuclear Information System (INIS)

    Qu, Ruijuan; Liu, Hongxia; Zhang, Qi; Flamm, Alison; Yang, Xi; Wang, Zunyao

    2012-01-01

    Highlights: ► The strength of the hydrogen bonds existed in PHOXTHs is ascertained. ► Good linear relations exist between the thermodynamic properties and N PHOS . ► The relative stability order of PHOXTH congeners is theoretically proposed. ► There is a good relation between C p,m and the temperature. - Abstract: There are three types of intramolecular hydrogen bonds with bond energy about 52 kJ mol −1 , 12 kJ mol −1 , 20 kJ mol −1 , respectively in PHOXTHs which were determined by computation on B3LYP/6-311G** level. The internal rotational potentials of the hydroxy group of 1-MHOXTH and 4′-MHOXTH are evaluated, and the influences of the spatial orientation of the hydroxy groups on the intramolecular hydrogen bonds and molecular stability are illustrated. The standard enthalpy of formation (Δ f H θ ) and standard Gibbs energy of formation (Δ f G θ ) for the most stable conformation of 135 PHOXTHs are calculated by the combination of Gaussian 03 and isodesmic reactions and the theoretical order of relative stability is proposed according to the relative magnitude of calculated Δ f G θ values. In addition, the values of molar heat capacities at constant pressure (C p,m ) from 200 to 1000 K for PHOXTH congeners are calculated.

  15. Projective synchronization of a complex network with different fractional order chaos nodes

    International Nuclear Information System (INIS)

    Wang Ming-Jun; Wang Xing-Yuan; Niu Yu-Jun

    2011-01-01

    Based on the stability theory of the linear fractional order system, projective synchronization of a complex network is studied in the paper, and the coupling functions of the connected nodes are identified. With this method, the projective synchronization of the network with different fractional order chaos nodes can be achieved, besides, the number of the nodes does not affect the stability of the whole network. In the numerical simulations, the chaotic fractional order Lü system, Liu system and Coullet system are chosen as examples to show the effectiveness of the scheme. (general)

  16. 221 THE ROLE OF BIRTH ORDER IN SUBSTANCE RELATED ...

    African Journals Online (AJOL)

    Administrator

    centre. The second objective was to investigate whether psychological birth order (a .... Figure 1: A Bar graph presenting frequencies for Ordinal Birth Order. N. Mean. SD. .... children on ground of birth order or on whatever basis. By making ...

  17. Sliding Mode Control of Fractional-Order Delayed Memristive Chaotic System with Uncertainty and Disturbance

    Science.gov (United States)

    Ding, Da-Wei; Liu, Fang-Fang; Chen, Hui; Wang, Nian; Liang, Dong

    2017-12-01

    In this paper, a simplest fractional-order delayed memristive chaotic system is proposed in order to control the chaos behaviors via sliding mode control strategy. Firstly, we design a sliding mode control strategy for the fractional-order system with time delay to make the states of the system asymptotically stable. Then, we obtain theoretical analysis results of the control method using Lyapunov stability theorem which guarantees the asymptotic stability of the non-commensurate order and commensurate order system with and without uncertainty and an external disturbance. Finally, numerical simulations are given to verify that the proposed sliding mode control method can eliminate chaos and stabilize the fractional-order delayed memristive system in a finite time. Supported by the National Nature Science Foundation of China under Grant No. 61201227, Funding of China Scholarship Council, the Natural Science Foundation of Anhui Province under Grant No. 1208085M F93, 211 Innovation Team of Anhui University under Grant Nos. KJTD007A and KJTD001B

  18. Ractor stability monitor

    International Nuclear Information System (INIS)

    Takeuchi, Yutaka.

    1991-01-01

    A stability monitor for a BWR type reactor determines the index of stability by statistic processing of signals from an average power region monitor or the like, but it takes much time and the reliability thereof is not always high. Then, parameters such as reactor core power are measured on every sampling periods as observation data and pretreatments such as normalization are applied successively, to obtain monitored amount and store them successively. Differentiation coefficient relative to time are calculated by using the observed amount at present and that one sample period before, to evaluate on a phasal plane using the amount of observation and the differentiation coefficient with time on the axes of coordinate. As a result, information relative to the stability can be represented accurately, thereby enabling to monitor the stability at a high accuracy. Further, judgement for the condition considering the amplitude is conducted upon oscillation, thereby enabling to conduct control operation certainly. The operation in a region where it has been limited under great caution can be conducted appropriately and safely, enabling to conduct controlled operation of excellent economical property. (N.H.)

  19. Stability of attachment-related anxiety and avoidance and their relationships with the five-factor model and the psychobiological model of personality.

    Science.gov (United States)

    Picardi, Angelo; Caroppo, Emanuele; Toni, Alessandro; Bitetti, Daniela; Di Maria, Giuseppe

    2005-09-01

    The stability of attachment-related anxiety and avoidance and their relationship with influential personality models are issues worth further investigation. Studying discriminant validity with respect to aspects of personality deemed as prevalently heritable, such as temperament, is particularly important. Our aims were to examine the stability of attachment dimensions and to study their relationship with psychological distress, the Big Five factors, and temperament and character dimensions. The Experiences in Close Relationships (ECR) questionnaire, the State-Trait Anxiety Inventory (STAI), the Zung depression scale (ZDS), the Temperament and Character Inventory (TCI-125), and the Big Five Questionnaire (BFQ) were administered to 222 undergraduate and graduate students. After 1 month, 115 participants completed again the ECR, the STAI, and the ZDS. Attachment-related anxiety was modestly correlated with depression and anxiety, while attachment-related avoidance was modestly correlated with depression. The test-retest reliability of ECR scores was high. Changes in attachment-related anxiety were not related to changes in depression or anxiety, and changes in attachment-related avoidance were modestly correlated with changes in depression. In separate multiple regression models also including gender and age, attachment-related anxiety was correlated with harm avoidance, reward dependence, low novelty seeking, low self-directedness and low cooperativeness; low energy/extraversion and low emotional stability; attachment-related avoidance was correlated with low reward dependence and tended to be correlated with low self-directedness. These findings corroborate the reliability and the convergent and discriminant validity of the ECR, and support the notion that the attachment dimensions are only modestly related to psychological distress and are not redundant with constructs developed within influential personality models such as the five-factor model and the

  20. Stability measures in arid ecosystems

    Science.gov (United States)

    Nosshi, M. I.; Brunsell, N. A.; Koerner, S.

    2015-12-01

    Stability, the capacity of ecosystems to persist in the face of change, has proven its relevance as a fundamental component of ecological theory. Here, we would like to explore meaningful and quantifiable metrics to define stability, with a focus on highly variable arid and semi-arid savanna ecosystems. Recognizing the importance of a characteristic timescale to any definition of stability, our metrics will be focused scales from annual to multi-annual, capturing different aspects of stability. Our three measures of stability, in increasing order of temporal scale, are: (1) Ecosystem resistance, quantified as the degree to which the system maintains its mean state in response to a perturbation (drought), based on inter-annual variability in Normalized Difference Vegetation Index (NDVI). (2) An optimization approach, relevant to arid systems with pulse dynamics, that models vegetation structure and function based on a trade off between the ability to respond to resource availability and avoid stress. (3) Community resilience, measured as species turnover rate (β diversity). Understanding the nature of stability in structurally-diverse arid ecosystems, which are highly variable, yields theoretical insight which has practical implications.

  1. Self-esteem stability in relation to narcissism and psychological well-being

    OpenAIRE

    Saša Zorjan; Katja Košir

    2013-01-01

    The concept of self-esteem stability has an important role in the understanding of interpersonal and psychological functioning of individuals. The purpose of this study was to examine the relationship between self-esteem stability, narcissism and psychological well-being. A total of 178 participants (77% female) participated in this study. The average age of the participants was 20, with the ages ranging from 18 to 26 years. The participants completed the following scales and questionnaires: ...

  2. Calculations of axisymmetric stability of tokamak plasmas with active and passive feedback

    International Nuclear Information System (INIS)

    Ward, D.J.; Jardin, S.C.; Cheng, C.Z.

    1991-07-01

    A new linear MHD stability code, NOVA-W, has been developed in order to study feedback stabilization of the axisymmetric mode in deformable tokamak plasmas. The NOVA-W code is a modification of the non-variational MHD stability code NOVA that includes the effects of resistive passive conductors and active feedback circuits. The vacuum calculation has been reformulated in terms of the perturbed poloidal flux to allow the inclusion of perturbed toroidal currents outside the plasma. The boundary condition at the plasma-vacuum interface relates the instability displacement to the perturbed poloidal flux. This allows a solution of the linear MHD stability equations with the feedback effects included. The passive stability predictions of the code have been tested both against a simplified analytic model and against a different numerical calculation for a realistic tokamak configuration. The comparisons demonstrate the accuracy of the NOVA-W results. Active feedback calculations are performed for the CIT tokamak design demonstrating the effect of varying the position of the flux loops that provide the measurements of vertical displacement. The results compare well with those computed earlier using a less efficient nonlinear code. 37 refs., 13 figs

  3. Linear stability of tearing modes

    International Nuclear Information System (INIS)

    Cowley, S.C.; Kulsrud, R.M.; Hahm, T.S.

    1986-05-01

    This paper examines the stability of tearing modes in a sheared slab when the width of the tearing layer is much smaller than the ion Larmor radius. The ion response is nonlocal, and the quasineutrality retains its full integal form. An expansion procedure is introduced to solve the quasineutrality equation in powers of the width of the tearing layer over the ion Larmor radius. The expansion procedure is applied to the collisionless and semi-collisional tearing modes. The first order terms in the expansion we find to be strongly stabilizing. The physics of the mode and of the stabilization is discussed. Tearing modes are observed in experiments even though the slab theory predicts stability. It is proposed that these modes grow from an equilibrium with islands at the rational surfaces. If the equilibrium islands are wider than the ion Larmor radius, the mode is unstable when Δ' is positive

  4. Contributions to fuzzy polynomial techniques for stability analysis and control

    OpenAIRE

    Pitarch Pérez, José Luis

    2014-01-01

    The present thesis employs fuzzy-polynomial control techniques in order to improve the stability analysis and control of nonlinear systems. Initially, it reviews the more extended techniques in the field of Takagi-Sugeno fuzzy systems, such as the more relevant results about polynomial and fuzzy polynomial systems. The basic framework uses fuzzy polynomial models by Taylor series and sum-of-squares techniques (semidefinite programming) in order to obtain stability guarantees...

  5. Stability of mass hierarchy in locally supersymmetric grand unification

    International Nuclear Information System (INIS)

    Nishino, H.; Helayel-Neto, J.A.; Koh, I.G.

    1984-06-01

    Some locally supersymmetric SU(5) grand unified models with a sliding singlet and two pairs of 5sub(tilde) and 5sub(tilde)* Higgs multiplets are considered from the viewpoint of universal baryon asymmetry and the one-loop stability of mass hierarchy. A new mechanism based on ''sliding singlet reflection symmetry'' to avoid the problem of the mass hierarchical stability is proposed. The stability is shown up to two-loop levels for some models. All order stability is also discussed. (author)

  6. Soil aggregation and slope stability related to soil density, root length, and mycorrhiza

    Science.gov (United States)

    Graf, Frank; Frei, Martin

    2013-04-01

    Eco-engineering measures combine the use of living plants and inert mechanical constructions to protect slopes against erosion and shallow mass movement. Whereas in geotechnical engineering several performance standards and guidelines for structural safety and serviceability of construction exist, there is a lack of comparable tools in the field of ecological restoration. Various indicators have been proposed, including the fractal dimension of soil particle size distribution, microbiological parameters, and soil aggregate stability. We present results of an soil aggregate stability investigation and compare them with literature data of the angle of internal friction ?' which is conventionally used in slope stability analysis and soil failure calculation. Aggregate stability tests were performed with samples of differently treated moraine, including soil at low (~15.5 kN/m³) and high (~19.0 kN/m³) dry unit weight, soil planted with Alnus incana (White Alder) as well as the combination of soil planted with alder and inoculated with the mycorrhizal fungus Melanogaster variegatus s.l. After a 20 weeks growth period in a greenhouse, a total of 100 samples was tested and evaluated. Positive correlations were found between the soil aggregate stability and the three variables dry unit weight, root length per soil volume, and degree of mycorrhization. Based on robust statistics it turned out that dry unit weight and mycorrhization degree were strongest correlated with soil aggregate stability. Compared to the non-inoculated control plants, mycorrhized White Alder produced significantly more roots and higher soil aggregate stability. Furthermore, the combined biological effect of plant roots and mycorrhizal mycelia on aggregate stability on soil with low density (~15.5 kN/m³) was comparable to the compaction effect of the pure soil from 15.5 to ~19.0 kN/m³. Literature data on the effect of vegetation on the angle of internal friction ?' of the same moraine showed

  7. Robust Fuzzy Control for Fractional-Order Uncertain Hydroturbine Regulating System with Random Disturbances

    Directory of Open Access Journals (Sweden)

    Fengjiao Wu

    2016-01-01

    Full Text Available The robust fuzzy control for fractional-order hydroturbine regulating system is studied in this paper. First, the more practical fractional-order hydroturbine regulating system with uncertain parameters and random disturbances is presented. Then, on the basis of interval matrix theory and fractional-order stability theorem, a fuzzy control method is proposed for fractional-order hydroturbine regulating system, and the stability condition is expressed as a group of linear matrix inequalities. Furthermore, the proposed method has good robustness which can process external random disturbances and uncertain parameters. Finally, the validity and superiority are proved by the numerical simulations.

  8. BWR stability using a reduced dynamical model

    International Nuclear Information System (INIS)

    Ballestrin Bolea, J.M.; Blazquez, J.B.

    1990-01-01

    BWR stability can be treated with reduced order dynamical models. When the parameters of the model came from experimental data, the predictions are accurate. In this work an alternative derivation for the void fraction equation is made, but remarking the physical struct-ure of the parameters. As the poles of power/reactivity transfer function are related with the parameters, the measurement of the poles by other techniques such as noise analysis will lead to the parameters, but the system of equations in non-linear. Simple parametric calculat-ion of decay ratio are performed, showing why BWRs become unstable when they are operated at low flow and high power. (Author). 7 refs

  9. Structure-activity relationships between sterols and their thermal stability in oil matrix.

    Science.gov (United States)

    Hu, Yinzhou; Xu, Junli; Huang, Weisu; Zhao, Yajing; Li, Maiquan; Wang, Mengmeng; Zheng, Lufei; Lu, Baiyi

    2018-08-30

    Structure-activity relationships between 20 sterols and their thermal stabilities were studied in a model oil system. All sterol degradations were found to be consistent with a first-order kinetic model with determination of coefficient (R 2 ) higher than 0.9444. The number of double bonds in the sterol structure was negatively correlated with the thermal stability of sterol, whereas the length of the branch chain was positively correlated with the thermal stability of sterol. A quantitative structure-activity relationship (QSAR) model to predict thermal stability of sterol was developed by using partial least squares regression (PLSR) combined with genetic algorithm (GA). A regression model was built with R 2 of 0.806. Almost all sterol degradation constants can be predicted accurately with R 2 of cross-validation equals to 0.680. Four important variables were selected in optimal QSAR model and the selected variables were observed to be related with information indices, RDF descriptors, and 3D-MoRSE descriptors. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Numerical multistep methods for the efficient solution of quantum mechanics and related problems

    International Nuclear Information System (INIS)

    Anastassi, Z.A.; Simos, T.E.

    2009-01-01

    In this paper we present the recent development in the numerical integration of the Schroedinger equation and related systems of ordinary differential equations with oscillatory solutions, such as the N-body problem. We examine several types of multistep methods (explicit, implicit, predictor-corrector, hybrid) and several properties (P-stability, trigonometric fitting of various orders, phase fitting, high phase-lag order, algebraic order). We analyze the local truncation error and the stability of the methods. The error for the Schroedinger equation is also presented, which reveals the relation of the error to the energy. The efficiency of the methods is evaluated through the integration of five problems. Figures are presented and analyzed and some general conclusions are made. Code written in Maple is given for the development of all methods analyzed in this paper. Also the subroutines written in Matlab, that concern the integration of the methods, are presented.

  11. Deciphering the imprint of topology on nonlinear dynamical network stability

    International Nuclear Information System (INIS)

    Nitzbon, J; Schultz, P; Heitzig, J; Kurths, J; Hellmann, F

    2017-01-01

    Coupled oscillator networks show complex interrelations between topological characteristics of the network and the nonlinear stability of single nodes with respect to large but realistic perturbations. We extend previous results on these relations by incorporating sampling-based measures of the transient behaviour of the system, its survivability, as well as its asymptotic behaviour, its basin stability. By combining basin stability and survivability we uncover novel, previously unknown asymptotic states with solitary, desynchronized oscillators which are rotating with a frequency different from their natural one. They occur almost exclusively after perturbations at nodes with specific topological properties. More generally we confirm and significantly refine the results on the distinguished role tree-shaped appendices play for nonlinear stability. We find a topological classification scheme for nodes located in such appendices, that exactly separates them according to their stability properties, thus establishing a strong link between topology and dynamics. Hence, the results can be used for the identification of vulnerable nodes in power grids or other coupled oscillator networks. From this classification we can derive general design principles for resilient power grids. We find that striving for homogeneous network topologies facilitates a better performance in terms of nonlinear dynamical network stability. While the employed second-order Kuramoto-like model is parametrised to be representative for power grids, we expect these insights to transfer to other critical infrastructure systems or complex network dynamics appearing in various other fields. (paper)

  12. Finite Time Control for Fractional Order Nonlinear Hydroturbine Governing System via Frequency Distributed Model

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2016-01-01

    Full Text Available This paper studies the application of frequency distributed model for finite time control of a fractional order nonlinear hydroturbine governing system (HGS. Firstly, the mathematical model of HGS with external random disturbances is introduced. Secondly, a novel terminal sliding surface is proposed and its stability to origin is proved based on the frequency distributed model and Lyapunov stability theory. Furthermore, based on finite time stability and sliding mode control theory, a robust control law to ensure the occurrence of the sliding motion in a finite time is designed for stabilization of the fractional order HGS. Finally, simulation results show the effectiveness and robustness of the proposed scheme.

  13. Examining the effects of birth order on personality.

    Science.gov (United States)

    Rohrer, Julia M; Egloff, Boris; Schmukle, Stefan C

    2015-11-17

    This study examined the long-standing question of whether a person's position among siblings has a lasting impact on that person's life course. Empirical research on the relation between birth order and intelligence has convincingly documented that performances on psychometric intelligence tests decline slightly from firstborns to later-borns. By contrast, the search for birth-order effects on personality has not yet resulted in conclusive findings. We used data from three large national panels from the United States (n = 5,240), Great Britain (n = 4,489), and Germany (n = 10,457) to resolve this open research question. This database allowed us to identify even very small effects of birth order on personality with sufficiently high statistical power and to investigate whether effects emerge across different samples. We furthermore used two different analytical strategies by comparing siblings with different birth-order positions (i) within the same family (within-family design) and (ii) between different families (between-family design). In our analyses, we confirmed the expected birth-order effect on intelligence. We also observed a significant decline of a 10th of a SD in self-reported intellect with increasing birth-order position, and this effect persisted after controlling for objectively measured intelligence. Most important, however, we consistently found no birth-order effects on extraversion, emotional stability, agreeableness, conscientiousness, or imagination. On the basis of the high statistical power and the consistent results across samples and analytical designs, we must conclude that birth order does not have a lasting effect on broad personality traits outside of the intellectual domain.

  14. W-transform for exponential stability of second order delay differential equations without damping terms.

    Science.gov (United States)

    Domoshnitsky, Alexander; Maghakyan, Abraham; Berezansky, Leonid

    2017-01-01

    In this paper a method for studying stability of the equation [Formula: see text] not including explicitly the first derivative is proposed. We demonstrate that although the corresponding ordinary differential equation [Formula: see text] is not exponentially stable, the delay equation can be exponentially stable.

  15. Finite difference schemes for second order systems describing black holes

    International Nuclear Information System (INIS)

    Motamed, Mohammad; Kreiss, H-O.; Babiuc, M.; Winicour, J.; Szilagyi, B.

    2006-01-01

    In the harmonic description of general relativity, the principal part of Einstein's equations reduces to 10 curved space wave equations for the components of the space-time metric. We present theorems regarding the stability of several evolution-boundary algorithms for such equations when treated in second order differential form. The theorems apply to a model black hole space-time consisting of a spacelike inner boundary excising the singularity, a timelike outer boundary and a horizon in between. These algorithms are implemented as stable, convergent numerical codes and their performance is compared in a 2-dimensional excision problem

  16. Highly Ordered Periodic Au/TiO₂ Hetero-Nanostructures for Plasmon-Induced Enhancement of the Activity and Stability for Ethanol Electro-oxidation.

    Science.gov (United States)

    Jin, Zhao; Wang, Qiyu; Zheng, Weitao; Cui, Xiaoqiang

    2016-03-02

    The catalytic electro-oxidation of ethanol is the essential technique for direct alcohol fuel cells (DAFCs) in the area of alternative energy for the ability of converting the chemical energy of alcohol into the electric energy directly. Developing highly efficient and stable electrode materials with antipoisoning ability for ethanol electro-oxidation remains a challenge. A highly ordered periodic Au-nanoparticle (NP)-decorated bilayer TiO2 nanotube (BTNT) heteronanostructure was fabricated by a two-step anodic oxidation of Ti foil and the subsequent photoreduction of HAuCl4. The plasmon-induced charge separation on the heterointerface of Au/TiO2 electrode enhances the electrocatalytic activity and stability for the ethanol oxidation under visible light irradiation. The highly ordered periodic heterostructure on the electrode surface enhanced the light harvesting and led to the greater performance of ethanol electro-oxidation under irradiation compared with the ordinary Au NPs-decorated monolayer TiO2 nanotube (MTNT). This novel Au/TiO2 electrode also performed a self-cleaning property under visible light attributed to the enhanced electro-oxidation of the adsorbed intermediates. This light-driven enhancement of the electrochemical performances provides a development strategy for the design and construction of DAFCs.

  17. A new time–space domain high-order finite-difference method for the acoustic wave equation

    KAUST Repository

    Liu, Yang; Sen, Mrinal K.

    2009-01-01

    A new unified methodology was proposed in Finkelstein and Kastner (2007) [39] to derive spatial finite-difference (FD) coefficients in the joint time-space domain to reduce numerical dispersion. The key idea of this method is that the dispersion relation is completely satisfied at several designated frequencies. We develop this new time-space domain FD method further for 1D, 2D and 3D acoustic wave modeling using a plane wave theory and the Taylor series expansion. New spatial FD coefficients are frequency independent though they lead to a frequency dependent numerical solution. We prove that the modeling accuracy is 2nd-order when the conventional (2 M)th-order space domain FD and the 2nd-order time domain FD stencils are directly used to solve the acoustic wave equation. However, under the same discretization, the new 1D method can reach (2 M)th-order accuracy and is always stable. The 2D method can reach (2 M)th-order accuracy along eight directions and has better stability. Similarly, the 3D method can reach (2 M)th-order accuracy along 48 directions and also has better stability than the conventional FD method. The advantages of the new method are also demonstrated by the results of dispersion analysis and numerical modeling of acoustic wave equation for homogeneous and inhomogeneous acoustic models. In addition, we study the influence of the FD stencil length on numerical modeling for 1D inhomogeneous media, and derive an optimal FD stencil length required to balance the accuracy and efficiency of modeling. A new time-space domain high-order staggered-grid FD method for the 1D acoustic wave equation with variable densities is also developed, which has similar advantages demonstrated by dispersion analysis, stability analysis and modeling experiments. The methodology presented in this paper can be easily extended to solve similar partial difference equations arising in other fields of science and engineering. © 2009 Elsevier Inc.

  18. A new time–space domain high-order finite-difference method for the acoustic wave equation

    KAUST Repository

    Liu, Yang

    2009-12-01

    A new unified methodology was proposed in Finkelstein and Kastner (2007) [39] to derive spatial finite-difference (FD) coefficients in the joint time-space domain to reduce numerical dispersion. The key idea of this method is that the dispersion relation is completely satisfied at several designated frequencies. We develop this new time-space domain FD method further for 1D, 2D and 3D acoustic wave modeling using a plane wave theory and the Taylor series expansion. New spatial FD coefficients are frequency independent though they lead to a frequency dependent numerical solution. We prove that the modeling accuracy is 2nd-order when the conventional (2 M)th-order space domain FD and the 2nd-order time domain FD stencils are directly used to solve the acoustic wave equation. However, under the same discretization, the new 1D method can reach (2 M)th-order accuracy and is always stable. The 2D method can reach (2 M)th-order accuracy along eight directions and has better stability. Similarly, the 3D method can reach (2 M)th-order accuracy along 48 directions and also has better stability than the conventional FD method. The advantages of the new method are also demonstrated by the results of dispersion analysis and numerical modeling of acoustic wave equation for homogeneous and inhomogeneous acoustic models. In addition, we study the influence of the FD stencil length on numerical modeling for 1D inhomogeneous media, and derive an optimal FD stencil length required to balance the accuracy and efficiency of modeling. A new time-space domain high-order staggered-grid FD method for the 1D acoustic wave equation with variable densities is also developed, which has similar advantages demonstrated by dispersion analysis, stability analysis and modeling experiments. The methodology presented in this paper can be easily extended to solve similar partial difference equations arising in other fields of science and engineering. © 2009 Elsevier Inc.

  19. Physical and oxidative stability of high fat fish oil-in-water emulsions stabilized with combinations of sodium caseinate and sodium alginate

    DEFF Research Database (Denmark)

    Yesiltas, Betül; García Moreno, Pedro Jesús; Sørensen, Ann-Dorit Moltke

    2017-01-01

    .2 ratio NaCas:NaAlg by Box-Behnken's design, the formulae 70%-1.4%-1.2 was decided due to high fish oil content's decreasing effect on droplet size and peroxide value. Practical applications: Physically and oxidatively stable high fat (50-70%) omega-3 delivery fish oil-in-water emulsions are of high......A systematic study was carried out in order to evaluate the physical and oxidative stability of high fat omega-3 delivery fish oil-in-water emulsions stabilized with combinations of sodium caseinate (NaCas) and sodium alginate (NaAlg). The influence of 3 factors related to emulsion composition...... (fish oil content: 50, 60 and 70%; total amount of NaCas and NaAlg: 1.4, 2.1 and 2.8 %; and ratio NaCas:NaAlg: 0.4, 1.2 and 2) on physical (droplet size, viscosity and zeta potential) and oxidative (primary and secondary oxidation products) parameters was evaluated. It was possible to produce emulsions...

  20. Environmental constraints shaping constituent order in emerging communication systems: Structural iconicity, interactive alignment and conventionalization.

    Science.gov (United States)

    Christensen, Peer; Fusaroli, Riccardo; Tylén, Kristian

    2016-01-01

    Where does linguistic structure come from? Recent gesture elicitation studies have indicated that constituent order (corresponding to for instance subject-verb-object, or SVO in English) may be heavily influenced by human cognitive biases constraining gesture production and transmission. Here we explore the alternative hypothesis that syntactic patterns are motivated by multiple environmental and social-interactional constraints that are external to the cognitive domain. In three experiments, we systematically investigate different motivations for structure in the gestural communication of simple transitive events. The first experiment indicates that, if participants communicate about different types of events, manipulation events (e.g. someone throwing a cake) and construction events (e.g. someone baking a cake), they spontaneously and systematically produce different constituent orders, SOV and SVO respectively, thus following the principle of structural iconicity. The second experiment shows that participants' choice of constituent order is also reliably influenced by social-interactional forces of interactive alignment, that is, the tendency to re-use an interlocutor's previous choice of constituent order, thus potentially overriding affordances for iconicity. Lastly, the third experiment finds that the relative frequency distribution of referent event types motivates the stabilization and conventionalization of a single constituent order for the communication of different types of events. Together, our results demonstrate that constituent order in emerging gestural communication systems is shaped and stabilized in response to multiple external environmental and social factors: structural iconicity, interactive alignment and distributional frequency. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Hybrid High-Order methods for finite deformations of hyperelastic materials

    Science.gov (United States)

    Abbas, Mickaël; Ern, Alexandre; Pignet, Nicolas

    2018-01-01

    We devise and evaluate numerically Hybrid High-Order (HHO) methods for hyperelastic materials undergoing finite deformations. The HHO methods use as discrete unknowns piecewise polynomials of order k≥1 on the mesh skeleton, together with cell-based polynomials that can be eliminated locally by static condensation. The discrete problem is written as the minimization of a broken nonlinear elastic energy where a local reconstruction of the displacement gradient is used. Two HHO methods are considered: a stabilized method where the gradient is reconstructed as a tensor-valued polynomial of order k and a stabilization is added to the discrete energy functional, and an unstabilized method which reconstructs a stable higher-order gradient and circumvents the need for stabilization. Both methods satisfy the principle of virtual work locally with equilibrated tractions. We present a numerical study of the two HHO methods on test cases with known solution and on more challenging three-dimensional test cases including finite deformations with strong shear layers and cavitating voids. We assess the computational efficiency of both methods, and we compare our results to those obtained with an industrial software using conforming finite elements and to results from the literature. The two HHO methods exhibit robust behavior in the quasi-incompressible regime.

  2. Stability and change in structural social relations as predictor of mortality among elderly women and men

    DEFF Research Database (Denmark)

    Lund, Rikke; Modvig, J; Due, P

    2000-01-01

    In a follow-up study of 70-95 years old women and men (n = 911) we studied the association between change and stability in three structural aspects of social relations (contact frequency, contact diversity, cohabitation status) from 1986-1990 and mortality after the next four years in 1994. Women.......02-14.94) and ORdiv: 6.04 (1.30-28.03). In summary, we found rather larger age differences in the strength of the association between change in structural social relations and mortality. Furthermore, the associations seemed stronger among women than men, which may however mainly be explained by the small number...

  3. On the nonlinear stability of mKdV breathers

    Science.gov (United States)

    Alejo, Miguel A.; Muñoz, Claudio

    2012-11-01

    Breather modes of the mKdV equation on the real line are known to be elastic under collisions with other breathers and solitons. This fact indicates very strong stability properties of breathers. In this communication we describe a rigorous, mathematical proof of the stability of breathers under a class of small perturbations. Our proof involves the existence of a nonlinear equation satisfied by all breather profiles, and a new Lyapunov functional which controls the dynamics of small perturbations and instability modes. In order to construct such a functional, we work in a subspace of the energy one. However, our proof introduces new ideas in order to attack the corresponding stability problem in the energy space. Some remarks about the sine-Gordon case are also considered.

  4. Subharmonic Resonance of Van Der Pol Oscillator with Fractional-Order Derivative

    Directory of Open Access Journals (Sweden)

    Yongjun Shen

    2014-01-01

    Full Text Available The subharmonic resonance of van der Pol (VDP oscillator with fractional-order derivative is studied by the averaging method. At first, the first-order approximate solutions are obtained by the averaging method. Then the definitions of equivalent linear damping coefficient (ELDC and equivalent linear stiffness coefficient (ELSC for subharmonic resonance are established, and the effects of the fractional-order parameters on the ELDC, the ELSC, and the dynamical characteristics of system are also analysed. Moreover, the amplitude-frequency equation and phase-frequency equation of steady-state solution for subharmonic resonance are established. The corresponding stability condition is presented based on Lyapunov theory, and the existence condition for subharmonic resonance (ECSR is also obtained. At last, the comparisons of the fractional-order and the traditional integer-order VDP oscillator are fulfilled by the numerical simulation. The effects of the parameters in fractional-order derivative on the steady-state amplitude, the amplitude-frequency curves, and the system stability are also studied.

  5. Re-Shaping Treaties while Balancing Interests of Stability and Change : Trends in the Amendment/Modification/Revision of Treaties

    NARCIS (Netherlands)

    Merkouris, Panagiotis; Fitzmaurice, Malgosia

    2018-01-01

    The present article aims to examine the trends in amendment/modification/revision (A/M/R) practices in international law, and how these reflect the constant tug-of-war between the competing interests of stability of international relations and the necessity to change in order to avoid stagnation.

  6. Re-Shaping Treaties while Balancing Interests of Stability and Change : Trends in the Amendment/Modification/Revision of Treaties

    NARCIS (Netherlands)

    Merkouris, Panagiotis; Fitzmaurice, Malgosia

    2017-01-01

    The present article aims to examine the trends in amendment/modification/revision (A/M/R) practices in international law, and how these reflect the constant tug-of-war between the competing interests of stability of international relations and the necessity to change in order to avoid stagnation.

  7. Study of a high-order-mode gyrotron traveling-wave amplifier

    International Nuclear Information System (INIS)

    Chiu, C. C.; Tsai, C. Y.; Kao, S. H.; Chu, K. R.; Barnett, L. R.; Luhmann, N. C. Jr.

    2010-01-01

    Physics and performance issues of a TE 01 -mode gyrotron traveling-wave amplifier are studied in theory. For a high order mode, absolute instabilities on neighboring modes at the fundamental and higher cyclotron harmonic frequencies impose severe constraints to the device capability. Methods for their stabilization are outlined, on the basis of which the performance characteristics are examined in a multidimensional parameter space under the marginal stability criterion. The results demonstrate the viability of a high-order-mode traveling-wave amplifier and provide a roadmap for design tradeoffs among power, bandwidth, and efficiency. General trends are observed and illustrated with specific examples.

  8. Soil aggregate stability as an indicator for eco-engineering effectiveness?

    Science.gov (United States)

    Graf, Frank

    2015-04-01

    Eco-engineering aims at stabilising soil and slopes by applying technical and biological measures. Engineering structures are commonly well defined, immediately usable and operative, and their stability effects quantifiable and verifiable. Differently, the use of plants requires more restrictive boundary conditions and the protection potential is rarely easily calculable and develop-ing as a function of growth rate. Although the use of vegetation is widely appreciated and their stabilising effect recognised, there is an increasing demand on sound facts on its efficiency, in particular, in relation to time. Conclusively, a certain necessity has been recognised to monitor, assess and quantify the effectiveness of ecological restora-tion measures in order to facilitate the transfer of technology and knowledge. Recent theoretical models emphasize the im-portance of taking an integrated monitoring approach that considers multiple variables. However, limited financial and time resources often prevent such comprehensive assessments. A solution to this problem may be to use integrated indicators that reflect multiple aspects and, therefore, allow extensive information on ecosystem status to be gathered in a relatively short time. Among various other indicators, such as fractal dimension of soil particle size distribution or microbiological parameters, soil aggregate stability seems the most appropriate indicator with regard to protecting slopes from superficial soil failure as it is critical to both plant growth and soil structure. Soil aggregation processes play a crucial role in re-establishing soil structure and function and, conclusively, for successful and sustainable re-colonisation. Whereas the key role of soil aggregate stability in ecosystem functioning is well known concerning water, gas, and nutrient fluxes, only limited information is available with regard to soil mechanical and geotechnical aspects. Correspondingly, in the last couple of years several studies

  9. Projection-based stabilization of interface Lagrange multipliers in immersogeometric fluid-thin structure interaction analysis, with application to heart valve modeling.

    Science.gov (United States)

    Kamensky, David; Evans, John A; Hsu, Ming-Chen; Bazilevs, Yuri

    2017-11-01

    This paper discusses a method of stabilizing Lagrange multiplier fields used to couple thin immersed shell structures and surrounding fluids. The method retains essential conservation properties by stabilizing only the portion of the constraint orthogonal to a coarse multiplier space. This stabilization can easily be applied within iterative methods or semi-implicit time integrators that avoid directly solving a saddle point problem for the Lagrange multiplier field. Heart valve simulations demonstrate applicability of the proposed method to 3D unsteady simulations. An appendix sketches the relation between the proposed method and a high-order-accurate approach for simpler model problems.

  10. Adaptive generalized function matrix projective lag synchronization between fractional-order and integer-order complex networks with delayed coupling and different dimensions

    International Nuclear Information System (INIS)

    Dai, Hao; Si, Gangquan; Jia, Lixin; Zhang, Yanbin

    2013-01-01

    This paper investigates generalized function matrix projective lag synchronization between fractional-order and integer-order complex networks with delayed coupling, non-identical topological structures and different dimensions. Based on Lyapunov stability theory, generalized function matrix projective lag synchronization criteria are derived by using the adaptive control method. In addition, the three-dimensional fractional-order chaotic system and the four-dimensional integer-order hyperchaotic system as the nodes of the drive and the response networks, respectively, are analyzed in detail, and numerical simulation results are presented to illustrate the effectiveness of the theoretical results. (paper)

  11. Fixation stability and implication for multifocal electroretinography in patients with neovascular age-related macular degeneration after anti-VEGF treatment

    DEFF Research Database (Denmark)

    Pedersen, Karen Bjerg; Sjølie, Anne Katrin; Vestergaard, Anders Højslet

    2016-01-01

    Purpose: To quantify fixation stability in patients with neovascular age-related macular degeneration (nAMD) at baseline, 3 and 6 months after anti-vascular endothelial growth factor (anti-VEGF) treatment and furthermore asses the implications of an unsteady fixation for multifocal...

  12. Delayed feedback control of fractional-order chaotic systems

    International Nuclear Information System (INIS)

    Gjurchinovski, A; Urumov, V; Sandev, T

    2010-01-01

    We study the possibility to stabilize unstable steady states and unstable periodic orbits in chaotic fractional-order dynamical systems by the time-delayed feedback method. By performing a linear stability analysis, we establish the parameter ranges for successful stabilization of unstable equilibria in the plane parameterized by the feedback gain and the time delay. An insight into the control mechanism is gained by analyzing the characteristic equation of the controlled system, showing that the control scheme fails to control unstable equilibria having an odd number of positive real eigenvalues. We demonstrate that the method can also stabilize unstable periodic orbits for a suitable choice of the feedback gain, providing that the time delay is chosen to coincide with the period of the target orbit. In addition, it is shown numerically that delayed feedback control with a sinusoidally modulated time delay significantly enlarges the stability region of steady states in comparison to the classical time-delayed feedback scheme with a constant delay.

  13. Lyapunov stability and thermal stability of partially relaxed fluids and plasmas

    International Nuclear Information System (INIS)

    Elsaesser, K.; Spiess, P.

    1996-01-01

    The relation between the Lyapunov stability of a Hamiltonian system and the thermal stability of a fluid whose temperature is controlled from outside is explored: The free energy as a functional of the correct variables (specific volume, local entropy, and some Clebsch potentials of the velocity) may serve as a Lyapunov functional, depending on the open-quote open-quote Casimirs close-quote close-quote as exchanged quantities. For a multi-species plasma one obtains a sufficient condition for stability: γ(v 2 /c 2 s )-1 s the sound speed. Some features of partially relaxed (T=const) cylindrical plasmas are also discussed. copyright 1996 American Institute of Physics

  14. Stability and stabilization of nonlinear systems and Takagi-Sugeno's fuzzy models

    Directory of Open Access Journals (Sweden)

    Blanco Yann

    2001-01-01

    Full Text Available This paper outlines a methodology to study the stability of Takagi-Sugeno's (TS fuzzy models. The stability analysis of the TS model is performed using a quadratic Liapunov candidate function. This paper proposes a relaxation of Tanaka's stability condition: unlike related works, the equations to be solved are not Liapunov equations for each rule matrix, but a convex combination of them. The coefficients of this sums depend on the membership functions. This method is applied to the design of continuous controllers for the TS model. Three different control structures are investigated, among which the Parallel Distributed Compensation (PDC. An application to the inverted pendulum is proposed here.

  15. Reliability Analysis of Dynamic Stability in Waves

    DEFF Research Database (Denmark)

    Søborg, Anders Veldt

    2004-01-01

    exhibit sufficient characteristics with respect to slope at zero heel (GM value), maximum leverarm, positive range of stability and area below the leverarm curve. The rule-based requirements to calm water leverarm curves are entirely based on experience obtained from vessels in operation and recorded......The assessment of a ship's intact stability is traditionally based on a semi-empirical deterministic concept that evaluates the characteristics of ship's calm water restoring leverarm curves. Today the ship is considered safe with respect to dynamic stability if its calm water leverarm curves...... accidents in the past. The rules therefore only leaves little room for evaluation and improvement of safety of a ship's dynamic stability. A few studies have evaluated the probability of ship stability loss in waves using Monte Carlo simulations. However, since this probability may be in the order of 10...

  16. Relation between second-order moment radius of focal spot and near field distribution of laser beam

    International Nuclear Information System (INIS)

    Gao Xueyan; Su Yi; Ye Yidong; Guan Youguang

    2011-01-01

    In order to analyze the effect of aberration of amplitude and phase of laser beam on second-order moment radius of focal spot, based on the Fraunhofer formula for light wave scalar diffraction theory and the definition of second-order moment radius, the general expression for focal spot second-order moment radius depending on the complex amplitude of near field is derived. The second-order moment radius of the focal spot depending on intensity distribution and phase distribution of near field is derived, and its clear physical meaning is described. The second-order moment radius and the divergence angle of focal spot may be easily calculated with the second-order moment radius expression of focal spot. At last, the divergence angles of focal spots of several kinds of Gaussian laser beams are calculated directly, and the results are in accordance with those in the related references. (authors)

  17. Ash Stabilization Campaign Blend Plan

    International Nuclear Information System (INIS)

    Winstead, M.L.

    1995-01-01

    This Stabilization Blend Plan documents the material to be processed and the processing order for the FY95 Ash Stabilization Campaign. The primary mission of this process is to reduce the inventory of unstable plutonium bearing ash. The source of the ash is from Rocky Flats and the 232-Z incinerator at the Plutonium Finishing Plant (PFP). The ash is currently being stored in Room 235B and Vault 174 in building 234-5Z. The sludge is to be thermally stabilized in a glovebox in room 230A of the 234-5Z building and material handling for the process will be done in room 230B of the same building. The campaign is scheduled for approximately 12--16 weeks. A total of roughly 4 kg of Pu will be processed

  18. Stochastic description of cascade size effects on phase stability under irradiation

    International Nuclear Information System (INIS)

    Martin, G.; Bellon, P.

    1988-01-01

    Cascade size may affect phase stability under irradiation because of two distinct contributions: the replacement to displacement cross section ratio depends on the deposited energy density; ballistic jumps which tend to disorder ordere compounds occur by bursts (of size b), while thermal jumps which restored long range order occur one by one. The latter effect cannot be handled by standard rate theory. A stochastic treatment of the problem, based on a Fokker Planck approximation of the relevant master equation is summarized. It is shown that the possible values of the long range order parameter under irradiation are not affected by the size b of the bursts, but that the respective stability of the former is b dependent. As a consequence, the stability diagram of phases under irradiation varies with b. Such a diagram is computed for the Ni 4 Mo system where three structures are competing: the disordered solid solution, D1 a and DO 23 . A broadening by 100K of the stability domain of the short range ordered structure to the expense of the long range ordered one is predicted when increasing b from 1 to 100. The stochastic potentials introduced in the present treatment are by no means free energies of some constrained state. They can however be computed in a mean field type approximation. 23 refs

  19. Precipitation Effect on Mechanical Properties and Phase Stability of High Manganese Steel

    Science.gov (United States)

    Bae, Cheoljun; Kim, Rosa; Lee, Un-Hae; Kim, Jongryoul

    2017-09-01

    High manganese (Mn) steels are attractive for automotive applications due to their excellent tensile strength and superior elongation. However, the relatively low yield strength of Mn steels compared to other advanced high-strength steels is a critical problem limiting their use in structural parts. In order to increase the yield strength, the precipitation hardening effect of Mn steels was investigated by the addition of carbide-forming elements. Changes in the austenite phase stability were also evaluated in terms of stacking fault energy (SFE). As a result, fine V(C,N) precipitates were found to increase the yield strength effectively but to lower the SFE by the consumption of matrix carbons. For achieving precipitation hardening without sacrificing austenite stability, the soluble carbon content was discussed.

  20. Stability of generalized Runge-Kutta methods for stiff kinetics coupled differential equations

    International Nuclear Information System (INIS)

    Aboanber, A E

    2006-01-01

    A stability and efficiency improved class of generalized Runge-Kutta methods of order 4 are developed for the numerical solution of stiff system kinetics equations for linear and/or nonlinear coupled differential equations. The determination of the coefficients required by the method is precisely obtained from the so-called equations of condition which in turn are derived by an approach based on Butcher series. Since the equations of condition are fewer in number, free parameters can be chosen for optimizing any desired feature of the process. A further related coefficient set with different values of these parameters and the region of absolute stability of the method have been introduced. In addition, the A(α) stability properties of the method are investigated. Implementing the method in a personal computer estimated the accuracy and speed of calculations and verified the good performances of the proposed new schemes for several sample problems of the stiff system point kinetics equations with reactivity feedback

  1. Some results on stability of difference systems

    Directory of Open Access Journals (Sweden)

    Xiao-Song Yang

    2002-01-01

    Full Text Available This paper presents some new results on existence and stability of equilibrium or periodic points for difference systems. First sufficient conditions of existence of asymptotically stable equilibrium point as well as the asymptotic stability of given equilibrium point are given for second order or delay difference systems. Then some similar results on existence of asymptotically stable periodic (equilibrium points to general difference systems are presented.

  2. Axisymmetric stability of vertically asymmetric Tokamaks at large beta poloidal

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, K.; Fishman, H.; Okabayashi, M. (Princeton Univ., NJ (USA). Plasma Physics Lab.); Todd, A.M.M. (Grumman Aerospace Corp., Princeton, NJ (USA))

    1983-11-01

    The rigid-mode stability of high-..beta.. vertically asymmetric Tokamak equilibria with quasi-uniform current profile is investigated analytically using toroidicity-shaping double expansion method. It is found that vertical stability at large beta poloidal is mainly determined by a coupling between the shape of the plasma surface and the Shafranov shift of the magnetic axis. To the lowest order, symmetric components of the plasma surface shape are found to be the critical destabilizing elements. Asymmetric components have little effect. The inclusion of higher order terms in the high-..beta.. Tokamak expansion leads to further destabilization. These analytic insights are qualitatively confirmed by numerical stability calculations using the PEST code with parabolic safety-factor profile.

  3. Solubility and stability of inorganic carbonates

    International Nuclear Information System (INIS)

    Taylor, P.

    1987-01-01

    The chemistry of inorganic carbonates is reviewed, with emphasis on solubility and hydrolytic stability, in order to identify candidate waste forms for immobilization and disposal of 14 C. At present, CaCO 3 and BaCO 3 are the two most widely favoured wasted forms, primarily because they are the products of proven CO 2 -scrubbing technology. However, they have relatively high solubilities in non-alkaline solutions, necessitating care in selecting and assessing an appropriate disposal environment. Three compounds with better solubility characteristics in near-neutral waters are identified: bismutite, (BiO) 2 CO 3 ; hydrocerussite, Pb 3 (OH) 2 (CO 3 ) 2 ; and rhodochrosite, MnCO 3 . Some of the limitations of each of these alternative waste forms are discussed

  4. Development and validation of a stability-indicating RP-HPLC method for assay of betamethasone and estimation of its related compounds.

    Science.gov (United States)

    Fu, Qiang; Shou, Minshan; Chien, Dwight; Markovich, Robert; Rustum, Abu M

    2010-02-05

    Betamethasone (9alpha-fluoro-16beta-methylprednisolone) is one of the members of the corticosteriod family of active pharmaceutical ingredient (API), which is widely used as an anti-inflammatory agent and also as a starting material to manufacture various esters of betamethasone. A stability-indicating reverse-phase high performance liquid chromatography (RP-HPLC) method has been developed and validated which can separate and accurately quantitate low levels of 26 betamethasone related compounds. The stability-indicating capability of the method was demonstrated through adequate separation of all potential betamethasone related compounds from betamethasone and also from each other that are present in aged and stress degraded betamethasone stability samples. Chromatographic separation of betamethasone and its related compounds was achieved by using a gradient elution at a flow rate of 1.0mL/min on a ACE 3 C18 column (150mmx4.6mm, 3microm particle size, 100A pore size) at 40 degrees C. Mobile phase A of the gradient was 0.1% methanesulfonic acid in aqueous solution and mobile phase B was a mixture of tert-butanol and 1,4-dioxane (7:93, v/v). UV detection at 254nm was employed to monitor the analytes. For betamethasone 21-aldehyde, the QL and DL were 0.02% and 0.01% respectively. For betamethasone and the rest of the betamethasone related compounds, the QL and DL were 0.05% and 0.02%. The precision of betamethasone assay is 0.6% and the accuracy of betamethasone assay ranged from 98.1% to 99.9%.

  5. 36 CFR 902.51 - Records relating to matters that are required by Executive order to be kept secret.

    Science.gov (United States)

    2010-07-01

    ... that are required by Executive order to be kept secret. 902.51 Section 902.51 Parks, Forests, and... order to be kept secret. Records relating to matters that are specifically authorized under criteria established by an Executive order to be kept secret in the interest of national defense or foreign policy...

  6. Examination of changes in pathology tests ordered by Diagnosis-Related Group (DRGs) following CPOE introduction.

    Science.gov (United States)

    Vecellio, Elia; Georgiou, Andrew; Toouli, George; Eigenstetter, Alex; Li, Ling; Wilson, Roger; Westbrook, Johanna I

    2013-01-01

    Electronic test ordering, via the Electronic Medical Record (EMR), which incorporates computerised provider order entry (CPOE), is widely considered as a useful tool to support appropriate pathology test ordering. Diagnosis-related groups (DRGs) are clinically meaningful categories that allow comparisons in pathology utilisation by patient groups by controlling for many potentially confounding variables. This study used DRG data linked to pathology test data to examine changes in rates of test ordering across four years coinciding with the introduction of an EMR in six hospitals in New South Wales, Australia. This method generated a list of high pathology utilisation DRGs. We investigated patients with a Chest pain DRG to examine whether tests rates changed for specific test groups by hospital emergency department (ED) pre- and post-EMR. There was little change in testing rates between EDs or between time periods pre- and post-EMR. This is a valuable method for monitoring the impact of EMR and clinical decision support on test order rates.

  7. Linear and nonlinear Stability analysis for finite difference discretizations of higher order Boussinesq equations

    DEFF Research Database (Denmark)

    Fuhrmann, David R.; Bingham, Harry B.; Madsen, Per A.

    2004-01-01

    of rotational and irrotational formulations in two horizontal dimensions provides evidence that the irrotational formulation has significantly better stability properties when the deep-water nonlinearity is high, particularly on refined grids. Computation of matrix pseudospectra shows that the system is only...... insight into into the numerical behavior of this rather complicated system of nonlinear PDEs....

  8. Design guidelines for high dimensional stability of CFRP optical bench

    Science.gov (United States)

    Desnoyers, Nichola; Boucher, Marc-André; Goyette, Philippe

    2013-09-01

    In carbon fiber reinforced plastic (CFRP) optomechanical structures, particularly when embodying reflective optics, angular stability is critical. Angular stability or warping stability is greatly affected by moisture absorption and thermal gradients. Unfortunately, it is impossible to achieve the perfect laminate and there will always be manufacturing errors in trying to reach a quasi-iso laminate. Some errors, such as those related to the angular position of each ply and the facesheet parallelism (for a bench) can be easily monitored in order to control the stability more adequately. This paper presents warping experiments and finite-element analyses (FEA) obtained from typical optomechanical sandwich structures. Experiments were done using a thermal vacuum chamber to cycle the structures from -40°C to 50°C. Moisture desorption tests were also performed for a number of specific configurations. The selected composite material for the study is the unidirectional prepreg from Tencate M55J/TC410. M55J is a high modulus fiber and TC410 is a new-generation cyanate ester designed for dimensionally stable optical benches. In the studied cases, the main contributors were found to be: the ply angular errors, laminate in-plane parallelism (between 0° ply direction of both facesheets), fiber volume fraction tolerance and joints. Final results show that some tested configurations demonstrated good warping stability. FEA and measurements are in good agreement despite the fact that some defects or fabrication errors remain unpredictable. Design guidelines to maximize the warping stability by taking into account the main dimensional stability contributors, the bench geometry and the optical mount interface are then proposed.

  9. Survivin counteracts the therapeutic effect of microtubule de-stabilizers by stabilizing tubulin polymers

    Directory of Open Access Journals (Sweden)

    Hsieh Hsing-Pang

    2009-07-01

    Full Text Available Abstract Background Survivin is a dual function protein. It inhibits the apoptosis of cells by inhibiting caspases, and also promotes cell growth by stabilizing microtubules during mitosis. Over-expression of survivin has been demonstrated to induce drug-resistance to various chemo-therapeutic agents such as cisplatin (DNA damaging agent and paclitaxel (microtubule stabilizer in cancers. However, survivin-induced resistance to microtubule de-stabilizers such as Vinca alkaloids and Combretastatin A-4 (CA-4-related compounds were seldom demonstrated in the past. Furthermore, the question remains as to whether survivin plays a dominant role in processing cytokinesis or inhibiting caspases activity in cells treated with anti-mitotic compounds. The purpose of this study is to evaluate the effect of survivin on the resistance and susceptibility of human cancer cells to microtubule de-stabilizer-induced cell death. Results BPR0L075 is a CA-4 analog that induces microtubule de-polymerization and subsequent caspase-dependent apoptosis. To study the relationship between the expression of survivin and the resistance to microtubule de-stabilizers, a KB-derived BPR0L075-resistant cancer cell line, KB-L30, was generated for this study. Here, we found that survivin was over-expressed in the KB-L30 cells. Down-regulation of survivin by siRNA induced hyper-sensitivity to BPR0L075 in KB cells and partially re-stored sensitivity to BPR0L075 in KB-L30 cells. Western blot analysis revealed that down-regulation of survivin induced microtubule de-stabilization in both KB and KB-L30 cells. However, the same treatment did not enhance the down-stream caspase-3/-7 activities in BPR0L075-treated KB cells. Translocation of a caspase-independent apoptosis-related molecule, apoptosis-inducing factor (AIF, from cytoplasm to the nucleus was observed in survivin-targeted KB cells under BPR0L075 treatment. Conclusion In this study, survivin plays an important role in the

  10. Characteristics of attention-related body sensations. Temporal stability and associations with measures of body focus, affect, sustained attention, and heart rate variability.

    Science.gov (United States)

    Tihanyi, Benedek T; Ferentzi, Eszter; Köteles, Ferenc

    2017-09-01

    This study investigated the temporal stability and correlates of attention-related body sensations that emerge without external stimulation during rest and due to focused attention on a body part. To assess attention-related body sensations, participants were asked to focus on a freely chosen body area with closed eyes, and had to report whether the sensation of that area had changed. Self-report questionnaires were used to assess various aspects of body focus (body awareness, body responsiveness, somatosensory amplification, subjective somatic symptoms), and positive and negative affectivity. Previous experiences in body-mind therapies were also measured. PEBL Continuous Performance Test was used to assess sustained attention. Heart rate variability scores were based on a 3-minute long resting heart rate measurement. Fifty-eight university students (22.3 ± 3.95 years; 34 females) participated in the study. The stability of attention-related body sensations was measured 8 weeks later on a randomly chosen sub-group (n = 28). Attention-related body sensations showed a mediocre temporal stability (r ρ  = 0.47, p = 0.012). People reporting attention-related body sensations showed significantly higher body awareness, somatosensory amplification, and resting heart rate; and marginally higher somatic symptoms. No relation was found with body-mind practice, body responsiveness, positive and negative affect, the vagal component of heart rate variability, and performance in the sustained attention task. Attention-related sensations are relatively stable over time. They are connected to some, but not to all of the aspects of body focus. Further studies are needed to elaborate the influencing stable and situational factors.

  11. Synergistic effect of metal deactivator and antioxidant on oxidation stability of metal contaminated Jatropha biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Sarin, Amit [Department of Applied Sciences, Amritsar College of Engineering and Technology, Amritsar 143001 (India); Arora, Rajneesh; Singh, N.P. [Punjab Technical University, Jalandhar (India); Sarin, Rakesh; Malhotra, R.K. [Indian Oil Corporation Ltd., R and D Centre, Sector-13, Faridabad 121007 (India); Sharma, Meeta [Indian Oil Corporation Ltd., R and D Centre, Sector-13, Faridabad 121007 (India); University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Kashmere Gate, Delhi 110403 (India); Khan, Arif Ali [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Kashmere Gate, Delhi 110403 (India)

    2010-05-15

    Biodiesel is relatively unstable on storage and European biodiesel standard EN-14214 calls for determining oxidation stability at 110 C with a minimum induction time of 6 h by the Rancimat method (EN-14112). According to proposed National Mission on biodiesel in India, we have undertaken studies on stability of biodiesel from tree borne non-edible oil seeds Jatropha. Neat Jatropha biodiesel exhibited oxidation stability of 3.95 h. It is found possible to meet the desired EN specification for neat Jatropha biodiesel and metal contaminated Jatropha biodiesel by using antioxidants; it will have a cost implication, as antioxidants are costly chemicals. Research was conducted to increase the oxidation stability of metal contaminated Jatropha biodiesel by doping metal deactivator with antioxidant, with varying concentrations in order to meet the aforementioned standard required for oxidation stability. It was found that usage of antioxidant can be reduced by 30-50%, therefore the cost, even if very small amount of metal deactivator is doped in Jatropha biodiesel to meet EN-14112 specification. (author)

  12. Thermal stability of morpholine, AMP and sarcosine in PWR secondary systems. Laboratory and loop experiments

    International Nuclear Information System (INIS)

    Feron, D.; Lambert, I.

    1991-01-01

    Laboratory and loop tests have been carried out in order to investigate the thermal stability of three amines (morpholine, AMP and sarcosine) in PWR secondary conditions. Laboratory experiments have been performed in a titanium autoclave at 300 deg C. The results pointed out high thermal decomposition rates of AMP and sarcosine. A decomposition mechanism is proposed for the 3 amines. Loop tests have been performed in order to compare steam cycle conditioning with ammonia, morpholine and AMP. The amine concentrations and the decomposition products such as acetate and formate have been followed around the secondary circuit of the ORION loop which reproduces the main physico-chemical characteristics of a PWR secondary circuit. These concentrations are reported together with the evolution of cationic conductivities. The influence of oxygen concentration on amine thermal stability has been observed. Results are expressed also in terms of decomposition rates and of relative volatility

  13. Bunched beam longitudinal stability

    International Nuclear Information System (INIS)

    Baartman, R.

    1991-05-01

    Instabilities driven by narrow-band impedances can be stabilized by Landau damping arising from the synchrotron frequency spread due to the nonlinearity of the rf wave-form. We calculate stability diagrams for various phase space distributions. We find that distributions without tails are unstable in the 'negative mass' regime (inductive impedance below transition or capacitive impedance above transition). We also find that longitudinal instability thresholds of the (usually neglected) higher order radial modes are lower than expected. For example, the next to lowest dipole mode has a lower threshold than the lowest sextupole mode even though the latter has the larger growth rate in the absence of Landau damping. (Author) 5 refs., 5 figs

  14. Higher-Order Squeezing of Quantum Field and the Generalized Uncertainty Relations in Non-Degenerate Four-Wave Mixing

    Science.gov (United States)

    Li, Xi-Zeng; Su, Bao-Xia

    1996-01-01

    It is found that the field of the combined mode of the probe wave and the phase-conjugate wave in the process of non-degenerate four-wave mixing exhibits higher-order squeezing to all even orders. And the generalized uncertainty relations in this process are also presented.

  15. 75 FR 80553 - Self-Regulatory Organizations; NYSE Amex LLC; Order Approving a Proposed Rule Change Relating to...

    Science.gov (United States)

    2010-12-22

    ... SECURITIES AND EXCHANGE COMMISSION [Release No. 34-63558; File No. SR-NYSEAmex-2010-100] Self-Regulatory Organizations; NYSE Amex LLC; Order Approving a Proposed Rule Change Relating to Complex Orders December 16, 2010. I. Introduction On October 20, 2010, NYSE Amex LLC (``NYSE Amex'' or the ``Exchange...

  16. BWR stability using a reducing dynamical model

    International Nuclear Information System (INIS)

    Ballestrin Bolea, J. M.; Blazquez Martinez, J. B.

    1990-01-01

    BWR stability can be treated with reduced order dynamical models. When the parameters of the model came from dynamical models. When the parameters of the model came from experimental data, the predictions are accurate. In this work an alternative derivation for the void fraction equation is made, but remarking the physical structure of the parameters. As the poles of power/reactivity transfer function are related with the parameters, the measurement of the poles by other techniques such as noise analysis will lead to the parameters, but the system of equations is non-linear. Simple parametric calculation of decay ratio are performed, showing why BWRs become unstable when they are operated at low flow and high power. (Author)

  17. Related research on corneal higher-order aberrations after different ways refractive surgery

    Directory of Open Access Journals (Sweden)

    Shu-Xi He

    2015-08-01

    Full Text Available AIM:To evaluate the changes of corneal high-order aberration(including Coma, Spab, RMShafter laser in situ keratomileusis(LASIKwith femtosecond laser, sub-Bowman keratomileusis(SBKand laser epithelial keratomileusis(LASEK.METHODS: Of 82 myopic patients(164 eyes, 31 patients(62 eyeswere treated by FS-LASIK, 31 patients(62 eyeswere treated by SBK, 20 patients(40 eyeswere treated by LASEK. Sirius system was used for measuring the coma aberration, spherical aberration, and high order aberration at 1, 15d,1, 3mo after surgery.RESULTS: 1Vision: The uncorrected visual acuity of the three groups had no differences(P>0.05. 2Corneal aberrations: Three kinds of surgical procedure for patients with corneal aberration had significant impact. The C7, C8, C12 and RMSh of three groups were increased significantly(P0.05. The C7, C8, C12 and RMSh were not recovered to preoperative levels after 3mo. But the increase of patients after FS-LASIK was smaller than the other two groups, with statistical significance(P0.05.CONCLUSION: Compared with SBK and LASEK,FS-LASIK has better visual acuity in the early postoperative and corneal higher-order aberrations increase is relatively small.

  18. New Formula for Stability of Cube Armoured Roundheads

    DEFF Research Database (Denmark)

    Maciñeira, Enrique; Burcharth, Hans F.

    2009-01-01

    The paper presents a new formula for the stability of cube armoured roundheads. The formula is based on physical model tests in Aalborg University which both long crested and short crested waves of different wave steepness were used. The slope of the radius of the head were varied in order...... to explore the influence of the geometry on the armour stability. Besides cubes with mass density 2.4 t/m3, cubes with mass density 2.80 t/m3 were used in order to include the effect of mass density in the formula. The damage predictions given by the formula have been compared with prototype hand...

  19. A New Fractional-Order Chaotic Complex System and Its Antisynchronization

    Directory of Open Access Journals (Sweden)

    Cuimei Jiang

    2014-01-01

    with phase portraits, bifurcation diagrams, the histories, and the largest Lyapunov exponents. And we find that chaos exists in this system with orders less than 5 by numerical simulation. Additionally, antisynchronization of different fractional-order chaotic complex systems is considered based on the stability theory of fractional-order systems. This new system and the fractional-order complex Lorenz system can achieve antisynchronization. Corresponding numerical simulations show the effectiveness and feasibility of the scheme.

  20. Physical Stability of Freeze-Dried Isomalt Diastereomer Mixtures

    DEFF Research Database (Denmark)

    Koskinen, Anna-Kaisa; Fraser-Miller, Sara J.; Bøtker, Johan P.

    2016-01-01

    Purpose Isomalt is a sugar alcohol used as an excipient in commercially available solid oral dosage forms. The potential of isomalt as a novel freeze-drying excipient was studied in order to increase knowledge of the behavior of isomalt when it is freeze-dried. Methods Isomalt was freeze-dried in......Purpose Isomalt is a sugar alcohol used as an excipient in commercially available solid oral dosage forms. The potential of isomalt as a novel freeze-drying excipient was studied in order to increase knowledge of the behavior of isomalt when it is freeze-dried. Methods Isomalt was freeze......-dried in four different diastereomer compositions and its physical stability was investigated with differential scanning calorimetry, Fourier-transform infrared and Raman spectroscopy, X-ray powder diffraction, Karl-Fischer titration and thermogravimetric analysis in order to verify the solid state form...... of the diastereomer compositions showed signs of physical instability when stored in the highest relative humidity condition. The four different crystalline diastereomer mixtures showed specific identifiable solid state properties. Conclusions Isomalt was shown to be a suitable excipient for freeze-drying. Preferably...

  1. Long-term manure amendments reduced soil aggregate stability via redistribution of the glomalin-related soil protein in macroaggregates

    Science.gov (United States)

    Xie, Hongtu; Li, Jianwei; Zhang, Bin; Wang, Lianfeng; Wang, Jingkuan; He, Hongbo; Zhang, Xudong

    2015-01-01

    Glomalin-related soil protein (GRSP) contributes to the formation and maintenance of soil aggregates, it is however remains unclear whether long-term intensive manure amendments alter soil aggregates stability and whether GRSP regulates these changes. Based on a three-decade long fertilization experiment in northeast China, this study examined the impact of long-term manure input on soil organic carbon (SOC), total and easily extractable GRSP (GRSPt and GRSPe) and their respective allocations in four soil aggregates (>2000 μm; 2000–250 μm; 250–53 μm; and soil and SOC in each aggregate generally increased with increasing manure input, GRSPt and GRSPe in each aggregate showed varying changes with manure input. Both GRSP in macroaggregates (2000–250 μm) were significantly higher under low manure input, a pattern consistent with changes in soil aggregate stability. Constituting 38~49% of soil mass, macroaggregates likely contributed to the nonlinear changes of aggregate stability under manure amendments. The regulatory process of GRSP allocations in soil aggregates has important implications for manure management under intensive agriculture. PMID:26423355

  2. Stability of Tokamaks with respect to slip motions

    International Nuclear Information System (INIS)

    Rebhan, E.; Salat, A.

    1976-06-01

    Using the energy principle in Tokamaks we investigate a class of perturbations which, if unstable, cannot be stabilized by the toroidal main field. On the assumptions of usual Tokamak ordering and in the limit of infinite aspect ratio, these perturbations are shown to be minimizing among all axisymmetric perturbations. In the case of finite aspect ratio, a detailed stability analysis is carried out using a constant pressure surface current model with elliptic, triangular or rectangular plasma cross-section. Definite stabilization by toroidal effects and by beta poloidal is demonstrated. (orig.) [de

  3. Competing order parameters in Fermi systems with engineered band dispersion

    Science.gov (United States)

    Wu, Chien-Te; Boyack, Rufus; Anderson, Brandon; Levin, K.

    We explore a variety of competing phases in 2D and 3D Fermi gases in the presence of novel dispersion relations resulting from a shaken optical lattice. We incorporate spin imbalance along with attractive interactions. In 3D, at the mean field level we present phase diagrams reflecting the stability of alternative order parameters in the pairing (including LOFF) and charge density wave channels. We perform analogous studies in 2D, where we focus on the competition between different paired phases. Important in this regard is that our 2D studies are consistent with the Mermin Wagner theorem, so that, while there is competition, conventional superfluidity cannot occur

  4. Studies of beam position monitor stability

    International Nuclear Information System (INIS)

    Tenenbaum, P.

    1998-05-01

    The authors present the result s from two studies of the time stability between the mechanical center of a beam position monitor and its electrical/electronic center. In the first study, a group of 93 BPM processors was calibrated via Test Pulse Generator once per hour in order to measure the contribution of the readout electronics to offset drifts. In the second study, a triplet of stripline BPMs in the Final Focus Test Beam, separated only by drift spaces, was read out every 6 minutes during 1 week of beam operation. In both cases offset stability was observed to be on the order of microns over time spans ranging from hours to days, although during the beam study much worse performance was also observed. Implications for the beam position monitor system of future linear collider systems are discussed

  5. Transverse stability of Kawahara solitons

    DEFF Research Database (Denmark)

    Karpman, V.I.

    1993-01-01

    The transverse stability of the planar solitons described by the fifth-order Korteweg-de Vries equation (Kawahara solitons) is studied. It is shown that the planar solitons are unstable with respect to bending if the coefficient at the fifth-derivative term is positive and stable if it is negative...

  6. Frequency-Weighted Balancing Related Controller Reduction

    OpenAIRE

    Varga, Andras; Anderson, Brian D.O.

    2002-01-01

    The efficient solution of a class of controller approximation problems by using frequency-weighted balancing related model reduction approaches is considered. It is shown that for certain standard performance and stability enforcing frequency-weights, the computation of the frequency-weighted controllability and observability grammians can be done by solving reduced order Lyapunov equations regardless the controller itself is stable or unstable. The new approach can be used in conjunction wit...

  7. Unintended Transformations of Clinical Relations with a Computerized Physician Order Entry System

    DEFF Research Database (Denmark)

    Wentzer, Helle; Böttger, Ulrich; Boye, Niels

    2007-01-01

    A socio-technical approach was used to study the qualitative effects of deploying a medication CPOE (Computerized Physician Order Entry System with no decision support) at two internal medical wards in a hospital in Denmark. Our results show spatial and temporal transformations of core acts...... and relations in medication work, i.e. of the intended use of the system inscribed in hardware and software, in the relations of care between doctors and patients, of collaboration between doctors and nurses, and prospectively of the patients’ trajectories when readmitted to hospital or another health care...... or ‘doing medication’. The paper argues for the project organization to support the local collaboration and renegotiation of time and place of enacting medication with CPOE, as well as set up feedback for maturation of the software for future clinical use....

  8. Does waiting pay off for couples?: Partnership duration prior to household formation and union stability

    Directory of Open Access Journals (Sweden)

    Christine Schnor

    2015-09-01

    Full Text Available Background: Most couples that live together began their relationship while having separate addresses. In contrast to the large body of literature on the role of pre-marital cohabitation in divorce, very little is known about how the partnership period before moving in together affects union stability. Objective: This article investigates: 1 the timing of household formation in a couple's history, 2 the impact of such timing on dissolution behavior, and 3 how household formation and dissolution differ for first and higher-order partnerships. Methods: Using data based on 15,081 partnerships (of which 45Š were coresidential unions from the German Family Panel, cumulative incidence curves reveal the dynamic of the non-coresidential partnership episode. For the sample of coresidential unions (N=6,741, piecewise constant survival models with a person-specific frailty term are estimated in order to assess the influence of household formation timing on union stability. Results: Partnership arrangements with partners living in separate households are transitory in nature and may result in either household formation or separation. First partnerships transform into coresidential unions less often and later than higher-order partnerships. Union stability is positively related to the duration of the preceding non-coresidential period. Especially among unions with a non-coresidential period of 7 to 24 months, first partnerships have lower dissolution risks than higher-order partnerships. Conclusions: The results suggest that the non-coresidential period is a significant phase in the partnership, as it enables couples to acquire information about the quality of their partnership.

  9. A Stabilized Incompressible SPH Method by Relaxing the Density Invariance Condition

    Directory of Open Access Journals (Sweden)

    Mitsuteru Asai

    2012-01-01

    Full Text Available A stabilized Incompressible Smoothed Particle Hydrodynamics (ISPH is proposed to simulate free surface flow problems. In the ISPH, pressure is evaluated by solving pressure Poisson equation using a semi-implicit algorithm based on the projection method. Even if the pressure is evaluated implicitly, the unrealistic pressure fluctuations cannot be eliminated. In order to overcome this problem, there are several improvements. One is small compressibility approach, and the other is introduction of two kinds of pressure Poisson equation related to velocity divergence-free and density invariance conditions, respectively. In this paper, a stabilized formulation, which was originally proposed in the framework of Moving Particle Semi-implicit (MPS method, is applied to ISPH in order to relax the density invariance condition. This formulation leads to a new pressure Poisson equation with a relaxation coefficient, which can be estimated by a preanalysis calculation. The efficiency of the proposed formulation is tested by a couple of numerical examples of dam-breaking problem, and its effects are discussed by using several resolution models with different particle initial distances. Also, the effect of eddy viscosity is briefly discussed in this paper.

  10. Vehicle lateral dynamics stabilization using active suspension

    Directory of Open Access Journals (Sweden)

    Drobný V.

    2008-12-01

    Full Text Available The paper deals with the investigation of active nonlinear suspension control in order to stabilize the lateral vehicle motion in similar way as systems like ESP do. The lateral stabilization of vehicle based on braking forces can be alternatively provided by the different setting of suspension forces. The basis of this control is the nonlinear property of the tyres. The vehicle has at least four wheels and it gives one or more redundant vertical forces that can be used for the different distribution of vertical suspension forces in such a way that resulting lateral and/or longitudinal forces create the required correction moment for lateral dynamic vehicle stabilization.

  11. Stability analysis of zigzag boron nitride nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Rai, Hari Mohan, E-mail: rai.2208@gmail.com; Late, Ravikiran; Saxena, Shailendra K.; Kumar, Rajesh; Sagdeo, Pankaj R. [Indian Institute of Technology, Indore –452017 (India); Jaiswal, Neeraj K. [Discipline of Physics, PDPM- Indian Institute of Information Technology, Design and Manufacturing, Jabalpur – 482005 (India); Srivastava, Pankaj [Computational Nanoscience and Technology Lab. (CNTL), ABV- Indian Institute of Information Technology and Management, Gwalior – 474015 (India)

    2015-05-15

    We have explored the structural stability of bare and hydrogenated zigzag boron nitride nanoribbons (ZBNNRs). In order to investigate the structural stability, we calculate the cohesive energy for bare, one-edge and both edges H-terminated ZBNNRs with different widths. It is found that the ZBNNRs with width Nz=8 are energetically more favorable than the lower-width counterparts (Nz<8). Bare ZBNNRs have been found energetically most stable as compared to the edge terminated ribbons. Our analysis reveals that the structural stability is a function of ribbon-width and it is not affected significantly by the type of edge-passivation (one-edge or both-edges)

  12. Exponential Stability of Switched Positive Homogeneous Systems

    Directory of Open Access Journals (Sweden)

    Dadong Tian

    2017-01-01

    Full Text Available This paper studies the exponential stability of switched positive nonlinear systems defined by cooperative and homogeneous vector fields. In order to capture the decay rate of such systems, we first consider the subsystems. A sufficient condition for exponential stability of subsystems with time-varying delays is derived. In particular, for the corresponding delay-free systems, we prove that this sufficient condition is also necessary. Then, we present a sufficient condition of exponential stability under minimum dwell time switching for the switched positive nonlinear systems. Some results in the previous literature are extended. Finally, a numerical example is given to demonstrate the effectiveness of the obtained results.

  13. Dynamic analysis of high-order Cohen-Grossberg neural networks with time delay

    International Nuclear Information System (INIS)

    Chen Zhang; Zhao Donghua; Ruan Jiong

    2007-01-01

    In this paper, a class of high-order Cohen-Grossberg neural networks with time delay is studied. Several sufficient conditions are obtained for global asymptotic stability and global exponential stability using Lyapunov and LMI method. Finally, two examples are given to illustrate the effectiveness of our method

  14. The phase equilibria and thermal stability of the long-period stacking ordered phase in the Mg–Cu–Y system

    International Nuclear Information System (INIS)

    Jiang, Min; Su, Xiulan; Li, Hongxiao; Ren, Yuping; Qin, Gaowu

    2014-01-01

    Highlights: • 14H LPSO structure has been confirmed to be stable in the Mg–Cu–Y system. • Partial isothermal sections of the Mg–Cu–Y system from 300 to 450 °C have been established. • Reaction L + α-Mg ↔ 14H + Mg 2 Cu has been determined in the Mg–Cu–Y system. • The thermal stability of the 14H phase in the Mg–Cu–Y system has been well studied. - Abstract: Phase equilibria in the Mg-rich Mg–Cu–Y system at 300, 400 and 450 °C have been experimentally investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), electron probe micro-analyzer (EPMA) and transmission electron microscope (TEM). The results show that a long-period stacking ordered (LPSO) phase 14H is stable in the Mg–Cu–Y system, which is the only one ternary intermetallic compound that gets a thermodynamic equilibrium with the a-Mg phase. The equilibrium 14H phase has a very limited solid solution range, and can be nearly regarded as a ternary stoichiometric compound with a formulae as Mg 91 Cu 4 Y 5 . The thermal stability of the 14H phase in the Mg–Cu–Y system has been well studied, which shows that the 14H phase disappears varying from 442 °C to 490 °C depending on the alloy composition. The isothermal sections of the Mg-rich Mg–Cu–Y system at 300, 400 and 450 °C have been finally established, and moreover, a quasi-peritectic reaction L + α-Mg ↔ 14H + Mg 2 Cu has been determined occurring at 442 °C with an estimated liquid composition of Mg 77 Cu 18 Y 5

  15. A validated stability-indicating RP-HPLC method for levofloxacin in the presence of degradation products, its process related impurities and identification of oxidative degradant.

    Science.gov (United States)

    Lalitha Devi, M; Chandrasekhar, K B

    2009-12-05

    The objective of current study was to develop a validated specific stability indicating reversed-phase liquid chromatographic method for the quantitative determination of levofloxacin as well as its related substances determination in bulk samples, pharmaceutical dosage forms in the presence of degradation products and its process related impurities. Forced degradation studies were performed on bulk sample of levofloxacin as per ICH prescribed stress conditions using acid, base, oxidative, water hydrolysis, thermal stress and photolytic degradation to show the stability indicating power of the method. Significant degradation was observed during oxidative stress and the degradation product formed was identified by LCMS/MS, slight degradation in acidic stress and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies and the impurity spiked solution. Good resolution between the peaks corresponds to process related impurities and degradation products from the analyte were achieved on ACE C18 column using the mobile phase consists a mixture of 0.5% (v/v) triethyl amine in sodium dihydrogen orthophosphate dihydrate (25 mM; pH 6.0) and methanol using a simple linear gradient. The detection was carried out at 294 nm. The limit of detection and the limit of quantitation for the levofloxacin and its process related impurities were established. The stressed test solutions were assayed against the qualified working standard of levofloxacin and the mass balance in each case was in between 99.4 and 99.8% indicating that the developed LC method was stability indicating. Validation of the developed LC method was carried out as per ICH requirements. The developed LC method was found to be suitable to check the quality of bulk samples of levofloxacin at the time of batch release and also during its stability studies (long term and accelerated stability).

  16. Evaluating hepatocellular carcinoma cell lines for tumour samples using within-sample relative expression orderings of genes.

    Science.gov (United States)

    Ao, Lu; Guo, You; Song, Xuekun; Guan, Qingzhou; Zheng, Weicheng; Zhang, Jiahui; Huang, Haiyan; Zou, Yi; Guo, Zheng; Wang, Xianlong

    2017-11-01

    Concerns are raised about the representativeness of cell lines for tumours due to the culture environment and misidentification. Liver is a major metastatic destination of many cancers, which might further confuse the origin of hepatocellular carcinoma cell lines. Therefore, it is of crucial importance to understand how well they can represent hepatocellular carcinoma. The HCC-specific gene pairs with highly stable relative expression orderings in more than 99% of hepatocellular carcinoma but with reversed relative expression orderings in at least 99% of one of the six types of cancer, colorectal carcinoma, breast carcinoma, non-small-cell lung cancer, gastric carcinoma, pancreatic carcinoma and ovarian carcinoma, were identified. With the simple majority rule, the HCC-specific relative expression orderings from comparisons with colorectal carcinoma and breast carcinoma could exactly discriminate primary hepatocellular carcinoma samples from both primary colorectal carcinoma and breast carcinoma samples. Especially, they correctly classified more than 90% of liver metastatic samples from colorectal carcinoma and breast carcinoma to their original tumours. Finally, using these HCC-specific relative expression orderings from comparisons with six cancer types, we identified eight of 24 hepatocellular carcinoma cell lines in the Cancer Cell Line Encyclopedia (Huh-7, Huh-1, HepG2, Hep3B, JHH-5, JHH-7, C3A and Alexander cells) that are highly representative of hepatocellular carcinoma. Evaluated with a REOs-based prognostic signature for hepatocellular carcinoma, all these eight cell lines showed the same metastatic properties of the high-risk metastatic hepatocellular carcinoma tissues. Caution should be taken for using hepatocellular carcinoma cell lines. Our results should be helpful to select proper hepatocellular carcinoma cell lines for biological experiments. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. On Sequences of Numbers and Polynomials Defined by Linear Recurrence Relations of Order 2

    Directory of Open Access Journals (Sweden)

    Tian-Xiao He

    2009-01-01

    Full Text Available Here we present a new method to construct the explicit formula of a sequence of numbers and polynomials generated by a linear recurrence relation of order 2. The applications of the method to the Fibonacci and Lucas numbers, Chebyshev polynomials, the generalized Gegenbauer-Humbert polynomials are also discussed. The derived idea provides a general method to construct identities of number or polynomial sequences defined by linear recurrence relations. The applications using the method to solve some algebraic and ordinary differential equations are presented.

  18. Stability and related properties of vacua and ground states

    International Nuclear Information System (INIS)

    Wreszinski, Walter F.; Jaekel, Christian D.

    2008-01-01

    We consider the formal non-relativistic limit (nrl) of the :φ 4 : s+1 relativistic quantum field theory (rqft), where s is the space dimension. Following the work of R. Jackiw [R. Jackiw, in: A. Ali, P. Hoodbhoy (Eds.), Beg Memorial Volume, World Scientific, Singapore, 1991], we show that, for s = 2 and a given value of the ultraviolet cutoff κ, there are two ways to perform the nrl: (i) fixing the renormalized mass m 2 equal to the bare mass m 0 2 ; (ii) keeping the renormalized mass fixed and different from the bare mass m 0 2 . In the (infinite-volume) two-particle sector the scattering amplitude tends to zero as κ → ∞ in case (i) and, in case (ii), there is a bound state, indicating that the interaction potential is attractive. As a consequence, stability of matter fails for our boson system. We discuss why both alternatives do not reproduce the low-energy behaviour of the full rqft. The singular nature of the nrl is also nicely illustrated for s = 1 by a rigorous stability/instability result of a different nature

  19. Next to leading order three jet production at hadron colliders

    International Nuclear Information System (INIS)

    Kilgore, W.

    1997-01-01

    Results from a next-to-leading order event generator of purely gluonic jet production are presented. This calculation is the first step in the construction of a full next-to-leading order calculation of three jet production at hadron colliders. Several jet algorithms commonly used in experiments are implemented and their numerical stability is investigated. A numerical instability is found in the iterative cone algorithm which makes it inappropriate for use in fixed order calculations beyond leading order. (author)

  20. Formal Solutions for Polarized Radiative Transfer. II. High-order Methods

    Energy Technology Data Exchange (ETDEWEB)

    Janett, Gioele; Steiner, Oskar; Belluzzi, Luca, E-mail: gioele.janett@irsol.ch [Istituto Ricerche Solari Locarno (IRSOL), 6605 Locarno-Monti (Switzerland)

    2017-08-20

    When integrating the radiative transfer equation for polarized light, the necessity of high-order numerical methods is well known. In fact, well-performing high-order formal solvers enable higher accuracy and the use of coarser spatial grids. Aiming to provide a clear comparison between formal solvers, this work presents different high-order numerical schemes and applies the systematic analysis proposed by Janett et al., emphasizing their advantages and drawbacks in terms of order of accuracy, stability, and computational cost.

  1. Computer generated structures of grain boundaries in Li2-type ordered alloys

    International Nuclear Information System (INIS)

    DeHosson, J.Th.M.; Pestman, B.J.; Schapink, F.W.; Tichelaar, F.D.

    1988-01-01

    In recent years, the influence of the establishment of long-range order in cubic alloys on the structure of grain boundaries in Li 2 alloys has been considered. Thus, for example, for the Σ = 5 (310) tilt boundary the various possible structures have been investigated that are generated upon ordering, starting from plausible structures in the disordered state. However, apart from some rough energy estimates based upon nearest neighbor interactions, no reliable energy calculations have been performed of these different possible structures. In this paper, computer calculations based upon interatomic pair potentials constructed in such a way that the Li 2 structure is stable with respect to disordering, are reported for the Σ = 5 (310) boundary. The relative stability of various possible structures, with associated different boundary compositions, has been investigated

  2. Low-energy theorems for Compton scattering up to order e/sup 4/. [Scattering amplitudes dispersion relations

    Energy Technology Data Exchange (ETDEWEB)

    Pippig, G

    1975-01-01

    Taking the Compton scattering of pions and deuterons as an example it is shown that low-energy theorems which are valid for the order e/sup 2/ are also valid for the next higher order of electromagnetic interactions. The imaginary component of the scattering amplitude was exactly calculated for the energy of incident photons in the order e/sup 4/ up to the desired one, whereas the real component was obtained from dispersion relations. It is proved that the results derived from the dispersion theory of strong interactions are equivalent to those obtained from quantum electrodynamics for spin 0 and spin 1, respectively.

  3. Higher order structural effects stabilizing the reverse watson-crick guanine-cytosine base pair in functional RNAs

    KAUST Repository

    Chawla, Mohit

    2013-10-10

    The G:C reverse Watson-Crick (W:W trans) base pair, also known as Levitt base pair in the context of tRNAs, is a structurally and functionally important base pair that contributes to tertiary interactions joining distant domains in functional RNA molecules and also participates in metabolite binding in riboswitches. We previously indicated that the isolated G:C W:W trans base pair is a rather unstable geometry, and that dicationic metal binding to the Guanine base or posttranscriptional modification of the Guanine can increase its stability. Herein, we extend our survey and report on other H-bonding interactions that can increase the stability of this base pair. To this aim, we performed a bioinformatics search of the PDB to locate all the occurencies of G:C trans base pairs. Interestingly, 66% of the G:C trans base pairs in the PDB are engaged in additional H-bonding interactions with other bases, the RNA backbone or structured water molecules. High level quantum mechanical calculations on a data set of representative crystal structures were performed to shed light on the structural stability and energetics of the various crystallographic motifs. This analysis was extended to the binding of the preQ1 metabolite to a preQ1-II riboswitch. 2013 The Author(s).

  4. 222Rn concentration in the outdoor atmosphere and its relation to the atmospheric stability

    International Nuclear Information System (INIS)

    Holy, K.; Boehm, R.; Bosa, I.; Polaskova, A.; Hola, O.

    1998-01-01

    The radon in the outdoor atmosphere has been monitored continuously since 1991. On the basis of the measured data mainly the average daily and the average annual courses of the 222 Rn concentrations have been studied. The annual courses of 222 Rn concentration are similar for all years. They present the annual variations. The average course of the 222 Rn concentration calculated on the basis of all continual measurements in the years 1991-1997 reaches the maximum value in October and the minimum value in April. The average daily courses of the 222 Rn concentration for the individual months of the year. The average daily courses have a form of waves with a maximum in the morning hours and with a minimum in the afternoon. The maximal amplitudes of daily waves have been reached in the summer months, from June till August. The amplitudes of daily waves are very small at the end of an autumn and during the winter months. The analysis of the daily waves and annual courses of 222 Rn showed that the amplitudes of the daily waves are in proportion to the global solar radiation irradiating the Earth's surface. The day duration influence on the phase of the daily wave and the wind velocity influence mainly on the level of the radon concentration. For the study of the relation of the radon concentration in the outdoor atmosphere to the stability the data of the atmosphere were obtained and they were correlated with the radon concentration. The results indicate that the 222 Rn concentrations int he outdoor atmosphere could be used for determination of the vertical atmospheric stability and these ones could reflect the atmospheric stability more completely than the different classifications based on the knowledge pertinent to the meteorological parameters. (authors)

  5. Relative performance of three stream bed stability indices as indicators of stream health.

    Science.gov (United States)

    Kusnierz, Paul C; Holbrook, Christopher M

    2017-10-16

    Bed stability is an important stream habitat attribute because it affects geomorphology and biotic communities. Natural resource managers desire indices of bed stability that can be used under a wide range of geomorphic conditions, are biologically meaningful, and are easily incorporated into sampling protocols. To eliminate potential bias due to presence of instream wood and increase precision of stability values, we modified a stream bed instability index (ISI) to include measurements of bankfull depth (d bf ) and median particle diameter (D 50 ) only in riffles and increased the pebble count to decrease variability (i.e., increase precision) in D 50 . The new riffle-based instability index (RISI) was compared to two established indices: ISI and the riffle stability index (RSI). RISI and ISI were strongly associated with each other but neither was closely associated with RSI. RISI and ISI were closely associated with both a diatom- and two macrovertebrate-based stream health indices, but RSI was only weakly associated with the macroinvertebrate indices. Unexpectedly, precision of D 50 did not differ between RISI and ISI. Results suggest that RISI is a viable alternative to both ISI and RSI for evaluating bed stability in multiple stream types. With few data requirements and a simple protocol, RISI may also better conform to riffle-based sampling methods used by some water quality practitioners.

  6. Topological and Graph-Coloring Conditions on the Parameter-Independent Stability of Second-Order Networked Systems

    NARCIS (Netherlands)

    Koerts, Filip; Bürger, Mathias; van der Schaft, Abraham; De Persis, Claudio

    2017-01-01

    In this paper, we study parameter-independent stability in qualitatively heterogeneous passive networked systems containing damped and undamped nodes. Given the graph topology and a set of damped nodes, we ask if output consensus is achieved for all system parameter values. For given parameter

  7. Valence electron structure and properties of stabilized ZrO2

    Institute of Scientific and Technical Information of China (English)

    LI JinPing; HAN JieOai; MENG SongHe; ZHANG XingHong

    2008-01-01

    To reveal the properties of stabilizers in ZrO2 on nanoscopic levels,the valence elec-tron structures of four stable ZrO2 phases and c-ZrO2 were analyzed on the basis of the empirical electron theory of solids and molecules.The results showed that the hybridization levels of Zr atoms in c-ZrO2 doped with Ca and Mg dropped from B17 to B13,the hybridization levels of Zr atoms in c-ZrO2 doped with Y and Ce dropped from B17 to B15,and that the four stabilizing atoms all made the hybridization levels of O atoms drop from level 4 to level 2.The numbers of covalent electrons in the strongest covalent bond in the descending order are c-ZrO2>ZrCeO2>ZrYOZrMgO>ZrCaO.The bond energies of the strongest covalent bond and the melting points of the solid solutions in the descending order are ZrCeO2>c-ZrO2>ZrYO>ZrMgO>ZrCaO.The percent-ages of the total number of covalent electrons in the descending order arec-ZrO2>ZrYO> ZrCeO2>ZrMgO> ZrCaO.From the above analysis,it can be concluded that the stabilizing degrees of the four stabilizers in the descending order are CaO> MgO>Y2O3>CeO2.

  8. Variational formulation and stability analysis of a three dimensional superelastic model for shape memory alloys

    Science.gov (United States)

    Alessi, Roberto; Pham, Kim

    2016-02-01

    This paper presents a variational framework for the three-dimensional macroscopic modelling of superelastic shape memory alloys in an isothermal setting. Phase transformation is accounted through a unique second order tensorial internal variable, acting as the transformation strain. Postulating the total strain energy density as the sum of a free energy and a dissipated energy, the model depends on two material scalar functions of the norm of the transformation strain and a material scalar constant. Appropriate calibration of these material functions allows to render a wide range of constitutive behaviours including stress-softening and stress-hardening. The quasi-static evolution problem of a domain is formulated in terms of two physical principles based on the total energy of the system: a stability criterion, which selects the local minima of the total energy, and an energy balance condition, which ensures the consistency of the evolution of the total energy with respect to the external loadings. The local phase transformation laws in terms of Kuhn-Tucker relations are deduced from the first-order stability condition and the energy balance condition. The response of the model is illustrated with a numerical traction-torsion test performed on a thin-walled cylinder. Evolutions of homogeneous states are given for proportional and non-proportional loadings. Influence of the stress-hardening/softening properties on the evolution of the transformation domain is emphasized. Finally, in view of an identification process, the issue of stability of homogeneous states in a multi-dimensional setting is answered based on the study of second-order derivative of the total energy. Explicit necessary and sufficient conditions of stability are provided.

  9. WASTE STABILIZATION FUNDAMENTALS FOR BIOREACTOR LANDFILLS

    Science.gov (United States)

    Waste stabilization is the process where putrescible waste is biodegraded by microorganisms resulting in an end-product being a relatively inert substrate (e.g., like compost). When exposed to moisture, biologically stabilized waste should not produce substantial quantitie...

  10. Inverse synchronization of coupled fractional-order systems through ...

    Indian Academy of Sciences (India)

    netic waves [8], boundary layer effects in ducts [9], dielectric polarization [10], and ... fractional-order systems [27–34] due to its potential applications in secure ..... Now, according to the stability theorem of linear FDEs [61], we can derive the ...

  11. Improving the stability of coal slurries: Quarterly progress report for the period September 15, 1987-December 15, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Fogler, H.S.

    1987-01-01

    Gum tragacanth, GT changes the conformation on the negative surface of sulfate polystyrene latex particles as the amount of charge in GT alters with pH. Also, it had been indicated that the polygalacturonic acid, PGUA which constitutes the core of GT molecules is responsible for the conformational change. In order to find how this conformational change is related to the adsorption affinity between the surface and the polyelectrolyte, the positively charged amidine polystyrene latex particles were employed. The stability study showed that the PGUA can also stabilize the positively charged particles and that the stability of the amidine latex is virtually independent of pH whereas the stability of the sulfate latex is dependent on pH. The adsorption study indicated that this independence of stability on pH for the amidine latex is due to the fact that the strong adsorption affinity between the positive surface and the negative polyelectrolyte gives the similar conformation regardless of pH. 6 refs., 8 figs., 2 tabs.

  12. A Study on stabilization of energy supply and demand using foreign futures market

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Won Chul; Lee, Sung Keun [Korea Energy Economics Institute, Euiwang (Korea)

    1999-02-01

    This study seeks to minimize financial cost related to the price stabilization and the supply and demand stabilization. In order to accomplish this, it derives a theoretical model of supply hedging to minimize fluctuation risk of price and financial cost intended for crude oil and LNG. Through the positive analysis based on this, it analyzes quantitatively the economic effect of utilizing foreign futures market. It shows the decline of average and divergence of supply cost. Despite the economic effect of utilizing a futures market, the degree of utilizing energy futures market of related firms in Korea appeared to be insufficient. To raise the utilization of trading in futures, the followings were suggested. Firstly, cost reduction and sharing relating information can be designed through the joint participation among allied enterprises. Secondly, energy futures transaction center in Korea can be established or trading linkage based on the existing international trading system can be built. Thirdly, it is possible to subsidize related cost by making a loan from trading in futures. Lastly, the participating directly in a futures market at government level can be considered. (author). 61 refs., 57 figs., 22 tabs.

  13. Reduced order models inertial manifold and global bifurcations: searching instability boundaries in nuclear power systems

    International Nuclear Information System (INIS)

    Suarez Antola, R.

    2009-01-01

    In the framework of an analytic or numerical model of a BWR power plant, this could imply first to find an suitable approximation to the solution manifold of the differential equations describing the stability behaviour of this nonlinear system, and then a classification of the different solution types concerning their relation with the operational safety of the power plant, by distributing the different solution types in relation with the exclusion region of the power-flow map. Then the goal is to obtain the best attainable qualitative and quantitative global picture of plant dynamics. To do this, the construction and the analysis of the so called reduced order models (Rom) seems a necessary step. A reduced order model results after the full system of coupled nonlinear partial differential equations of the plant is reduced to a system of coupled nonlinear ordinary differential equations

  14. Chaos Suppression in Fractional order Permanent Magnet Synchronous Generator in Wind Turbine Systems

    Science.gov (United States)

    Rajagopal, Karthikeyan; Karthikeyan, Anitha; Duraisamy, Prakash

    2017-06-01

    In this paper we investigate the control of three-dimensional non-autonomous fractional-order uncertain model of a permanent magnet synchronous generator (PMSG) via a adaptive control technique. We derive a dimensionless fractional order model of the PMSM from the integer order presented in the literatures. Various dynamic properties of the fractional order model like eigen values, Lyapunov exponents, bifurcation and bicoherence are investigated. The system chaotic behavior for various orders of fractional calculus are presented. An adaptive controller is derived to suppress the chaotic oscillations of the fractional order model. As the direct Lyapunov stability analysis of the robust controller is difficult for a fractional order first derivative, we have derived a new lemma to analyze the stability of the system. Numerical simulations of the proposed chaos suppression methodology are given to prove the analytical results derived through which we show that for the derived adaptive controller and the parameter update law, the origin of the system for any bounded initial conditions is asymptotically stable.

  15. Separating method factors and higher order traits of the Big Five: a meta-analytic multitrait-multimethod approach.

    Science.gov (United States)

    Chang, Luye; Connelly, Brian S; Geeza, Alexis A

    2012-02-01

    Though most personality researchers now recognize that ratings of the Big Five are not orthogonal, the field has been divided about whether these trait intercorrelations are substantive (i.e., driven by higher order factors) or artifactual (i.e., driven by correlated measurement error). We used a meta-analytic multitrait-multirater study to estimate trait correlations after common method variance was controlled. Our results indicated that common method variance substantially inflates trait correlations, and, once controlled, correlations among the Big Five became relatively modest. We then evaluated whether two different theories of higher order factors could account for the pattern of Big Five trait correlations. Our results did not support Rushton and colleagues' (Rushton & Irwing, 2008; Rushton et al., 2009) proposed general factor of personality, but Digman's (1997) α and β metatraits (relabeled by DeYoung, Peterson, and Higgins (2002) as Stability and Plasticity, respectively) produced viable fit. However, our models showed considerable overlap between Stability and Emotional Stability and between Plasticity and Extraversion, raising the question of whether these metatraits are redundant with their dominant Big Five traits. This pattern of findings was robust when we included only studies whose observers were intimately acquainted with targets. Our results underscore the importance of using a multirater approach to studying personality and the need to separate the causes and outcomes of higher order metatraits from those of the Big Five. We discussed the implications of these findings for the array of research fields in which personality is studied.

  16. Power, stability of power, and creativity

    NARCIS (Netherlands)

    Sligte, Daniel J.; de Dreu, Carsten K. W.; Nijstad, Bernard A.

    Power hierarchies are an essential aspect of social organization, create stability and social order, and provide individuals with incentives to climb the hierarchical ladder. Extending previous work on power and creativity, we put forward that this relationship critically depends on both the

  17. Power, stability of power, and creativity

    NARCIS (Netherlands)

    Sligte, D.J.; de Dreu, C.K.W.; Nijstad, B.A.

    2011-01-01

    Power hierarchies are an essential aspect of social organization, create stability and social order, and provide individuals with incentives to climb the hierarchical ladder. Extending previous work on power and creativity, we put forward that this relationship critically depends on both the

  18. FINANCIAL STABILITY AS A FACTOR ECONOMIC SECURITY

    Directory of Open Access Journals (Sweden)

    A. V. Endovitskaya

    2015-01-01

    Full Text Available Summary. The article examines the linkages between financial stability and the level of its economic security. Considered the content of financial stability, represented by its own definition, we studied the basic conditions to achieve it. The logic diagram showing the location of financial stability and financial security to ensure the economic security of the business entity. A system of internal and external factors affecting the financial stability and endanger financial stability and financial security company. It has been established that it is the internal factors such as the availability of financial resources and financial position, capital structure, the company's ability to generate profits determine the level of economic security and its ability to withstand the negative impact of external and internal threats. The necessity of improving the financial sustainability in order to improve the economic security of the enterprise. On the basis of the research proposed matrix of risks affecting the financial stability and economic security, which allows to determine the probability of their occurrence and impact. It presents the economic, social, human, financial, organizational, economic, innovative and productive tools to increase the stability and financial security of an economic entity. List considered standard measures will make a plan of action to minimize the adverse impacts and enhance financial stability and security. Therefore, a prerequisite for the economic security of the enterprise is the attainment of financial stability.

  19. A stabilized second-order time accurate finite element formulation for incompressible viscous flow with heat transfer; Uma formulacao de elementos finitos estabilizada de segunda ordem no tempo para escoamentos viscosos com transferencia de calor

    Energy Technology Data Exchange (ETDEWEB)

    Curi, Marcos Filardy

    2011-07-01

    In view of the problem of global warming and the search for clean energy sources, a worldwide expansion on the use of nuclear energy is foreseen. Thus, the development of science and technology regarding nuclear power plants is essential, in particular in the field of reactor engineering. Fluid mechanics and heat transfer play an important role in the development of nuclear reactors. Computational Fluid Mechanics (CFD) is becoming ever more important in the optimization of cost and safety of the designs. This work presents a stabilized second-order time accurate finite element formulation for incompressible flows with heat transfer. A second order time discretization precedes a spatial discretization using finite elements. The terms that stabilize the finite element method arise naturally from the discretization process, rather than being introduced a priori in the variational formulation. The method was implemented in the program 'ns{sub n}ew{sub s}olvec2d{sub av}2{sub M}PI' written in FORTRAN90, developed in the Parallel Computing Laboratory at the Institute of Nuclear Engineering (LCP/IEN). Numerical solutions of some representative examples, including free, mixed and forced convection, demonstrate that the proposed stabilized formulation attains very good agreement with experimental and computational results available in the literature. (author)

  20. Optimization of the geometrical stability in square ring laser gyroscopes

    International Nuclear Information System (INIS)

    Santagata, R; Beghi, A; Cuccato, D; Belfi, J; Beverini, N; Virgilio, A Di; Ortolan, A; Porzio, A; Solimeno, S

    2015-01-01

    Ultra-sensitive ring laser gyroscopes are regarded as potential detectors of the general relativistic frame-dragging effect due to the rotation of the Earth. Our project for this goal is called GINGER (gyroscopes in general relativity), and consists of a ground-based triaxial array of ring lasers aimed at measuring the rotation rate of the Earth with an accuracy of 10 −14 rad s −1 . Such an ambitious goal is now within reach, as large-area ring lasers are very close to the required sensitivity and stability. However, demanding constraints on the geometrical stability of the optical path of the laser inside the ring cavity are required. Thus, we have begun a detailed study of the geometry of an optical cavity in order to find a control strategy for its geometry that could meet the specifications of the GINGER project. As the cavity perimeter has a stationary point for the square configuration, we identify a set of transformations on the mirror positions that allows us to adjust the laser beam steering to the shape of a square. We show that the geometrical stability of a square cavity strongly increases by implementing a suitable system to measure the mirror distances, and that the geometry stabilization can be achieved by measuring the absolute lengths of the two diagonals and the perimeter of the ring. (paper)

  1. THE IMPACT OF LIFESTYLE OF URBAN FAMILIES FOR ITS STABILITY

    Directory of Open Access Journals (Sweden)

    F. A. Igebaeva

    2016-01-01

    Full Text Available The paper presents an attempt to study the way a family depends on the nature and intensity of demographic processes, to identify relationship between reproduction and family behavior, its way of life (including reproductive behavior and stability. A specific status of a family as a social unit and a social institution in the population reproduction process is determined. Family functioning is considered in terms of overall reproduction process with its social meaning being as lifestyle reproduction and specific way of activities and behavior of different families in certain social conditions. There is analysis of changes in the nature of marriage and family relations as well as revealed factors that influence urban family life and marriage and divorce level. The article calls attention to the problem of stabilization and destabilization of urban families and the ways to regulate family relations. We offer a thesis on necessary measures to influence social opinion in order to make it healthier as well as public and social institutions to pay more attention at family issues and population reproduction. The paper is based on the results of the target sociological survey of two-parent families conducted by the author. 

  2. How to stabilize cilazapril-containing solid dosage forms? The optimization of a final drug formulation

    Directory of Open Access Journals (Sweden)

    Katarzyna Regulska

    2017-03-01

    Full Text Available Cilazapril, a moisture-sensitive compound, is known to undergo rapid degradation which could be additionally facilitated by the presence of excipients that contain or absorb moisture. Hence we investigated the stability of cilazapril in two commercially-available dosage forms and in binary mixtures with the selected excipients used in the studied commercial formulations i.e.: hypromellose, lactose monohydrate, maize starch and talc in order to detect any possible, stability-affecting incompatibilities. Also the impact of the blister made of oriented polyamide/aluminum/polyvinyl chloride//aluminum on cilazapril-containing tablets was researched. A validated HPLC and HPLC-MS methods were used for analysis and the isothermal stress testing conditions were applied (temperature range 318–343 K, relative humidity 76.4% for tablets and temperature 333 K, relative humidity range 50.9–76.4% for binary mixtures. It was shown that the degradation of cilazapril in both, model mixtures and tablets follows the autocatalytic model kinetics and it is more rapid than that observed for pure substance, evidenced by higher degradation rate constants. The immediate packaging protects cilazapril in tablets from degradation only in case of the original drug while in its blistered generic counterpart a slight but statistically insignificant increase of cilazapril decay occurs when compared to bare tablets (p < 0.05. The degradation product of cilazapril in tablets and binary mixtures was identified as cilazaprilat. It was also observed that the increase of relative humidity or the presence of hypromellose, lactose and talc significantly impairs the stability of cilazapril in the aforementioned order. Only maize starch exhibited a positive effect on cilazapril stability (10.8% loss of cilazapril in binary mixture after 360 days of stressing compared to 35% loss of pure cilazapril in analogous test conditions probably thanks to its moisture-scavenging properties

  3. Translational Influence on Messenger Stability

    DEFF Research Database (Denmark)

    Eriksen, Mette

    -termination to be a global phenomena in gene regulation. The influence of codon usage in the early coding region on messenger stability was examined, in order to establish how fast or slow the ribosome has to decode the sequence for it to protect the messenger from degradation. The experiments demonstrated that very fast...

  4. Understanding Financial Fluctuations and Their Relation to Macroeconomic Stability

    OpenAIRE

    Nora Guarata; Carolina Pagliacci

    2017-01-01

    This paper examines how financial fluctuations and macroeconomic stability interact in the case of Venezuela, acknowledging that financial conditions deteriorating the macroeconomic environment can arise with both good and bad macroeconomic performance. An empirical methodology is provided that constructs two indexes, which are fully interpretable and are constructed with a minimum set of assumptions applied to a large number of financial time series. Structural interpretation of indexes is p...

  5. Nolinear stability analysis of nuclear reactors : expansion methods for stability domains

    International Nuclear Information System (INIS)

    Yang, Chae Yong

    1992-02-01

    Two constructive methods for estimating asymptotic stability domains of nonlinear reactor models are developed in this study: an improved Chang and Thorp's method based on expansion of a Lyapunov function and a new method based on expansion of any positive definite function. The methods are established on the concept of stability definitions of Lyapunov itself. The first method provides a sequence of stability regions that eventually approaches the exact stability domain, but requires many expansions in order to obtain the entire stability region because the starting Lyapunov function usually corresponds to a small stability region and because most dynamic systems are stiff. The second method (new method) requires only a positive definite function and thus it is easy to come up with a starting region. From a large starting region, the entire stability region is estimated effectively after sufficient iterations. It is particularly useful for stiff systems. The methods are applied to several nonlinear reactor models known in the literature: one-temperature feedback model, two-temperature feedback model, and xenon dynamics model, and the results are compared. A reactor feedback model for a pressurized water reactor (PWR) considering fuel and moderator temperature effects is developed and the nonlinear stability regions are estimated for the various values of design parameters by using the new method. The steady-state properties of the nonlinear reactor system are analyzed via bifurcation theory. The analysis of nonlinear phenomena is carried out for the various forms of reactivity feedback coefficients that are both temperature- (or power-) independent and dependent. If one of two temperature coefficients is positive, unstable limit cycles or multiplicity of the steady-state solutions appear when the other temperature coefficient exceeds a certain critical value. As an example, even though the fuel temperature coefficient is negative, if the moderator temperature

  6. Quantifying Stability in Complex Networks: From Linear to Basin Stability

    Science.gov (United States)

    Kurths, Jürgen

    The human brain, power grids, arrays of coupled lasers and the Amazon rainforest are all characterized by multistability. The likelihood that these systems will remain in the most desirable of their many stable states depends on their stability against significant perturbations, particularly in a state space populated by undesirable states. Here we claim that the traditional linearization-based approach to stability is in several cases too local to adequately assess how stable a state is. Instead, we quantify it in terms of basin stability, a new measure related to the volume of the basin of attraction. Basin stability is non-local, nonlinear and easily applicable, even to high-dimensional systems. It provides a long-sought-after explanation for the surprisingly regular topologies of neural networks and power grids, which have eluded theoretical description based solely on linear stability. Specifically, we employ a component-wise version of basin stability, a nonlinear inspection scheme, to investigate how a grid's degree of stability is influenced by certain patterns in the wiring topology. Various statistics from our ensemble simulations all support one main finding: The widespread and cheapest of all connection schemes, namely dead ends and dead trees, strongly diminish stability. For the Northern European power system we demonstrate that the inverse is also true: `Healing' dead ends by addition of transmission lines substantially enhances stability. This indicates a crucial smart-design principle for tomorrow's sustainable power grids: add just a few more lines to avoid dead ends. Further, we analyse the particular function of certain network motifs to promote the stability of the system. Here we uncover the impact of so-called detour motifs on the appearance of nodes with a poor stability score and discuss the implications for power grid design. Moreover, it will be shown that basin stability enables uncovering the mechanism for explosive synchronization and

  7. Analysis of an Nth-order nonlinear differential-delay equation

    Science.gov (United States)

    Vallée, Réal; Marriott, Christopher

    1989-01-01

    The problem of a nonlinear dynamical system with delay and an overall response time which is distributed among N individual components is analyzed. Such a system can generally be modeled by an Nth-order nonlinear differential delay equation. A linear-stability analysis as well as a numerical simulation of that equation are performed and a comparison is made with the experimental results. Finally, a parallel is established between the first-order differential equation with delay and the Nth-order differential equation without delay.

  8. Real-Time Fixed-Order Lateral H2 Controller for Micro Air Vehicle

    Directory of Open Access Journals (Sweden)

    Meenakshi M.

    2011-01-01

    Full Text Available This paper presents the design and development of a fixed low-order, robust H2 controller for a micro air vehicle (MAV named Sarika-2. The controller synthesis uses strengthened discrete optimal projection equations and frequency-dependent performance index to achieve robust performance and stability. A single fixed gain low-order dynamic controller provides simultaneous stabilization, disturbance rejection, and sensor noise attenuation over the entire flight speed range of 16 m/sec to 26 m/sec. Comparative study indicates that the low-order H2-controller achieves robust performance levels similar to that of full order controller. Subsequently, the controller is implemented on a digital signal processor-based flight computer and is validated through the real time hardware in loop simulation. The responses obtained with hardware in loop simulation compares well with those obtained from the offline simulation.

  9. Marital stability and repartnering

    DEFF Research Database (Denmark)

    Martins, Mariana V; Costa, Patrício; Peterson, Brennan D

    2014-01-01

    a second union have higher initial levels of stress in their original relationship and higher changes in stress levels over the course of treatments. These findings suggest that high infertility-related stress levels before entering fertility treatment can negatively affect the stability of marital......OBJECTIVE: To compare the trajectories of infertility-related stress between patients who remain in the same relationship and patients who repartner. DESIGN: Longitudinal cohort study using latent growth modeling. SETTING: Fertility centers. PATIENT(S): Childless men and women evaluated before...... starting a new cycle of fertility treatment and observed for a 5-year period of unsuccessful treatments. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Marital stability and infertility-related stress. RESULT(S): The majority of patients (86%) remained with their initial partner, but 14% of participants...

  10. Recursive regularization step for high-order lattice Boltzmann methods

    Science.gov (United States)

    Coreixas, Christophe; Wissocq, Gauthier; Puigt, Guillaume; Boussuge, Jean-François; Sagaut, Pierre

    2017-09-01

    A lattice Boltzmann method (LBM) with enhanced stability and accuracy is presented for various Hermite tensor-based lattice structures. The collision operator relies on a regularization step, which is here improved through a recursive computation of nonequilibrium Hermite polynomial coefficients. In addition to the reduced computational cost of this procedure with respect to the standard one, the recursive step allows to considerably enhance the stability and accuracy of the numerical scheme by properly filtering out second- (and higher-) order nonhydrodynamic contributions in under-resolved conditions. This is first shown in the isothermal case where the simulation of the doubly periodic shear layer is performed with a Reynolds number ranging from 104 to 106, and where a thorough analysis of the case at Re=3 ×104 is conducted. In the latter, results obtained using both regularization steps are compared against the Bhatnagar-Gross-Krook LBM for standard (D2Q9) and high-order (D2V17 and D2V37) lattice structures, confirming the tremendous increase of stability range of the proposed approach. Further comparisons on thermal and fully compressible flows, using the general extension of this procedure, are then conducted through the numerical simulation of Sod shock tubes with the D2V37 lattice. They confirm the stability increase induced by the recursive approach as compared with the standard one.

  11. Large-Signal Lyapunov-Based Stability Analysis of DC/AC Inverters and Inverter-Based Microgrids

    Science.gov (United States)

    Kabalan, Mahmoud

    Microgrid stability studies have been largely based on small-signal linearization techniques. However, the validity and magnitude of the linearization domain is limited to small perturbations. Thus, there is a need to examine microgrids with large-signal nonlinear techniques to fully understand and examine their stability. Large-signal stability analysis can be accomplished by Lyapunov-based mathematical methods. These Lyapunov methods estimate the domain of asymptotic stability of the studied system. A survey of Lyapunov-based large-signal stability studies showed that few large-signal studies have been completed on either individual systems (dc/ac inverters, dc/dc rectifiers, etc.) or microgrids. The research presented in this thesis addresses the large-signal stability of droop-controlled dc/ac inverters and inverter-based microgrids. Dc/ac power electronic inverters allow microgrids to be technically feasible. Thus, as a prelude to examining the stability of microgrids, the research presented in Chapter 3 analyzes the stability of inverters. First, the 13 th order large-signal nonlinear model of a droop-controlled dc/ac inverter connected to an infinite bus is presented. The singular perturbation method is used to decompose the nonlinear model into 11th, 9th, 7th, 5th, 3rd and 1st order models. Each model ignores certain control or structural components of the full order model. The aim of the study is to understand the accuracy and validity of the reduced order models in replicating the performance of the full order nonlinear model. The performance of each model is studied in three different areas: time domain simulations, Lyapunov's indirect method and domain of attraction estimation. The work aims to present the best model to use in each of the three domains of study. Results show that certain reduced order models are capable of accurately reproducing the performance of the full order model while others can be used to gain insights into those three areas of

  12. Kinetic theory of magnetic island stability in tokamaks

    International Nuclear Information System (INIS)

    Zabiego, M.; Garbet, X.

    1993-10-01

    The non linear behavior of low and large wave number tearing modes is studied. The emphasis is layed on diamagnetic effects. A kinetic equation, including transport processes associated with a background of microturbulence, is used to describe the electron component. Such transport processes are shown to play a significant role in the adjustment of density and temperature profile and also in the calculation of the island rotation frequency. The fluctuating electric potential is calculated self-consistently, using the differential response of electrons and ions. Four regimes are considered, related to island width (smaller or larger than an ion Larmor radius) and transport regime (electron-ion collisions or electro-viscosity dominated). It is shown that diamagnetism does not influence the island stability for small island width in the viscous regime, as long as the constant A constraint is maintained. It turns out that the release of this constraint may strongly modify the previously calculated stability thresholds. Finally, it is found that diamagnetism is destabilizing (stabilizing) for island width smaller (larger) than an ion Larmor radius, in both resistive and viscous regimes. A typical island evolution scenario is studied which shows that even large scale tearing modes with positive Δ ' could saturate to island width of order of a few ion Larmor radii. Illustrative Δ ' threshold and island saturation size are calculated. (authors). 31 refs., 5 figs., 3 tabs

  13. Stabilization of marly soils with portland cement

    Science.gov (United States)

    Piskunov, Maksim; Karzin, Evgeny; Lukina, Valentina; Lukinov, Vitaly; Kholkin, Anatolii

    2017-10-01

    Stabilization of marlous soils with Portland cement will increase the service life of motor roads in areas where marl is used as a local road construction material. The result of the conducted research is the conclusion about the principal possibility of stabilization of marlous soils with Portland cement, and about the optimal percentage of the mineral part and the binding agent. When planning the experiment, a simplex-lattice plan was implemented, which makes it possible to obtain a mathematical model for changing the properties of a material in the form of polynomials of incomplete third order. Brands were determined for compressive strength according to GOST 23558-94 and variants of stabilized soils were proposed for road construction.

  14. Wind turbine power and sound in relation to atmospheric stability

    NARCIS (Netherlands)

    van den Berg, G. P.

    2008-01-01

    Atmospheric stability cannot, with respect to modem, toll wind turbines, be viewed as a 'small perturbation to a basic neutral state' This can be demonstrated by comparison of measured wind velocity at the height of the rotor with the wind velocity expected in a neutral or 'standard' atmosphere.

  15. Improving the stability of coal slurries: Quarterly progress report for the period June 15, 1987-September 15, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Fogler, H.S.

    1987-01-01

    Gum tragacanth, GT is a polysaccharide containing tragacanthic acid and arabinogalactan. In order to find which polysaccharide is responsible for the stabilization, the arabinogalactan and polygalacturonic acid were used in the flocculation test. The polygalacturonic acid is a linear polysaccharide which constitutes the core of tragacanthic acid that is branched polysaccharide. The much greater stabilization effect by polygalacturonic acid indicated that the tragacanthic acid is responsible for the stabilization by GT. More interestingly, the similar pH dependence of the stability was found for polygalacturonic acid as had been found for GT. The binding study indicated that this pH effect for polygalacturonic acid is due to the difference in the amount of adsorption whereas the pH effect for GT is due to the difference in the steric layer thickness with about the same amount of adsorption. This relative pH independence of amount of adsorption for GT indicates that the binding mechanism of GT is hydrophobic. In order to verify this, the hydrophilic latex was used in the adsorption study as well as hydrophobic latex. It was found that the amount of adsorption of GT for the hydrophilic latex was less than that for the hydrophobic sulfate polystyrene latex. 10 refs., 6 figs., 2 tabs.

  16. Carotid plaque age is a feature of plaque stability inversely related to levels of plasma insulin.

    Directory of Open Access Journals (Sweden)

    Sara Hägg

    Full Text Available BACKGROUND: The stability of atherosclerotic plaques determines the risk for rupture, which may lead to thrombus formation and potentially severe clinical complications such as myocardial infarction and stroke. Although the rate of plaque formation may be important for plaque stability, this process is not well understood. We took advantage of the atmospheric (14C-declination curve (a result of the atomic bomb tests in the 1950s and 1960s to determine the average biological age of carotid plaques. METHODOLOGY/PRINCIPAL FINDING: The cores of carotid plaques were dissected from 29 well-characterized, symptomatic patients with carotid stenosis and analyzed for (14C content by accelerator mass spectrometry. The average plaque age (i.e. formation time was 9.6±3.3 years. All but two plaques had formed within 5-15 years before surgery. Plaque age was not associated with the chronological ages of the patients but was inversely related to plasma insulin levels (p = 0.0014. Most plaques were echo-lucent rather than echo-rich (2.24±0.97, range 1-5. However, plaques in the lowest tercile of plaque age (most recently formed were characterized by further instability with a higher content of lipids and macrophages (67.8±12.4 vs. 50.4±6.2, p = 0.00005; 57.6±26.1 vs. 39.8±25.7, p<0.0005, respectively, less collagen (45.3±6.1 vs. 51.1±9.8, p<0.05, and fewer smooth muscle cells (130±31 vs. 141±21, p<0.05 than plaques in the highest tercile. Microarray analysis of plaques in the lowest tercile also showed increased activity of genes involved in immune responses and oxidative phosphorylation. CONCLUSIONS/SIGNIFICANCE: Our results show, for the first time, that plaque age, as judge by relative incorporation of (14C, can improve our understanding of carotid plaque stability and therefore risk for clinical complications. Our results also suggest that levels of plasma insulin might be involved in determining carotid plaque age.

  17. Stability of Scores on Super's Work Values Inventory-Revised

    Science.gov (United States)

    Leuty, Melanie E.

    2013-01-01

    Test-retest data on Super's Work Values Inventory-Revised for a group of predominantly White ("N" = 995) women (mean age = 23.5 years, SD = 8.07) and men (mean age = 21.5 years, SD = 5.80) showed stability in mean-level scores over a period of 1 year for the sample as a whole. However, low raw score and rank order stability coefficients…

  18. An Equal-Order DG Method for the Incompressible Navier-Stokes Equations

    KAUST Repository

    Cockburn, Bernardo

    2008-12-20

    We introduce and analyze a discontinuous Galerkin method for the incompressible Navier-Stokes equations that is based on finite element spaces of the same polynomial order for the approximation of the velocity and the pressure. Stability of this equal-order approach is ensured by a pressure stabilization term. A simple element-by-element post-processing procedure is used to provide globally divergence-free velocity approximations. For small data, we prove the existence and uniqueness of discrete solutions and carry out an error analysis of the method. A series of numerical results are presented that validate our theoretical findings. © 2008 Springer Science+Business Media, LLC.

  19. Linear Parameter Varying Versus Linear Time Invariant Reduced Order Controller Design of Turboprop Aircraft Dynamics

    Directory of Open Access Journals (Sweden)

    Widowati

    2012-07-01

    Full Text Available The applicability of parameter varying reduced order controllers to aircraft model is proposed. The generalization of the balanced singular perturbation method of linear time invariant (LTI system is used to reduce the order of linear parameter varying (LPV system. Based on the reduced order model the low-order LPV controller is designed by using synthesis technique. The performance of the reduced order controller is examined by applying it to lateral-directional control of aircraft model having 20th order. Furthermore, the time responses of the closed loop system with reduced order LPV controllers and reduced order LTI controller is compared. From the simulation results, the 8th order LPV controller can maintain stability and to provide the same level of closed-loop systems performance as the full-order LPV controller. It is different with the reduced-order LTI controller that cannot maintain stability and performance for all allowable parameter trajectories.

  20. Analytical modelling of resistive wall mode stabilization by rotation in toroidal tokamak plasmas

    International Nuclear Information System (INIS)

    Ham, C J; Gimblett, C G; Hastie, R J

    2011-01-01

    Stabilization of the resitive wall mode (RWM) may allow fusion power to be doubled for a given magnetic field in advanced tokamak operation. Experimental evidence from DIII-D and other machines suggests that plasma rotation can stabilize the RWM. Several authors (Finn 1995 Phys. Plasmas 2 3782, Bondeson and Xie 1997 Phys. Plasmas 4 2081) have constructed analytical cylindrical models for the RWM, but these do not deal with toroidal effects. The framework of Connor et al (1988 Phys. Fluids 31 577) is used to develop ideal plasma analytic models with toroidicity included. Stepped pressure profiles and careful ordering of terms are used to simplify the analysis. First, a current driven kink mode model is developed and a dispersion relation for arbitrary current profile is calculated. Second, the external pressure driven kink mode is similarly investigated as the most important RWM arises from this mode. Using this latter model it is found that the RWM is stabilized by Alfven continuum damping with rotation levels similar to those seen in experiments. An expression for the stability of the external kink mode for more general current profiles and a resistive wall is derived in the appendix.

  1. Stabilized helical peptides: overview of the technologies and its impact on drug discovery.

    Science.gov (United States)

    Klein, Mark

    2017-11-01

    Protein-protein interactions are predominant in the workings of all cells. Until now, there have been a few successes in targeting protein-protein interactions with small molecules. Peptides may overcome some of the challenges of small molecules in disrupting protein-protein interactions. However, peptides present a new set of challenges in drug discovery. Thus, the study of the stabilization of helical peptides has been extensive. Areas covered: Several technological approaches to helical peptide stabilization have been studied. In this review, stapled peptides, foldamers, and hydrogen bond surrogates are discussed. Issues regarding design principles are also discussed. Furthermore, this review introduces select computational techniques used to aid peptide design and discusses clinical trials of peptides in a more advanced stage of development. Expert opinion: Stabilized helical peptides hold great promise in a wide array of diseases. However, the field is still relatively new and new design principles are emerging. The possibilities of peptide modification are quite extensive and expanding, so the design of stabilized peptides requires great attention to detail in order to avoid a large number of failed lead peptides. The start of clinical trials with stapled peptides is a promising sign for the future.

  2. Stability properties of an anisotropic guiding center plasma and relation with the Suydam function

    International Nuclear Information System (INIS)

    Choe, J.Y.; Davidson, R.C.

    1979-01-01

    The effect of pressure anisotropy on the equilibrium and stability properties of an unstable guiding center plasma and the dependence of associated stability properties on the Suydam function S are examined. An explicit solution of the guiding center plasma equilibrium equation is obtained as a function of the anitsotropy parameter αequivalentP/sub parallel//P/sub perpendicular/ (assumed constant), and the maximum growth rates for internal kink modes are numerically computed for the entire permissible range of α. For a typical tokamak field configuration with shear in straight cylindrical geometry, it is found that the maximum growth rate is a monotonically increasing function of α. A detailed parameter study of equilibrium and stability properties is presented. The dependence of stability properties on the Suydam function S is investigated by correlating maximum growth rates with the magnitude of S, and by examining the ratio of consecutive eigenvalues for each set of the parameters. The numerical analysis shows that, even though the Suydam function occurs naturally in studies of marginal stability, the maximum growth rate (except for a narrow range of α) is a monotonically decreasing function of S

  3. ASDEX Upgrade-JT-60U comparison and ECRH power requirements for NTM stabilization in ITER

    International Nuclear Information System (INIS)

    Urso, L.; Zohm, H.; Maraschek, M.; Poli, E.; Isayama, A.

    2010-01-01

    Neoclassical tearing modes (NTMs) are experimentally controlled with local electron cyclotron current drive (ECCD) and the island width decay during NTM stabilization is modelled using the so-called modified Rutherford equation (MRE). In this paper, a modelling of the MRE is carried out and simulations of the island width decay are compared with the experimentally observed ones in order to fit the two free machine-independent parameters present in the equation. A systematic study on a database of NTM stabilization discharges from ASDEX Upgrade and JT-60U is done for extrapolating the ECCD power requirements for ITER. The extrapolation to ITER of the NTM stabilization results from ASDEX Upgrade and JT-60U shows that 10 MW of ECCD power are enough to stabilize large NTMs. The 10 MW power estimate for ITER is based on the assumption that the free parameters in the MRE are machine independent. Indeed, this assumption is verified in this paper for ASDEX Upgrade and JT-60U. An interesting consequence of the relatively modest power requirement for ITER is that the installed 20 MW will suffice for simultaneous 2/1 and 3/2 NTM stabilization.

  4. Mathematical modelling and linear stability analysis of laser fusion cutting

    International Nuclear Information System (INIS)

    Hermanns, Torsten; Schulz, Wolfgang; Vossen, Georg; Thombansen, Ulrich

    2016-01-01

    A model for laser fusion cutting is presented and investigated by linear stability analysis in order to study the tendency for dynamic behavior and subsequent ripple formation. The result is a so called stability function that describes the correlation of the setting values of the process and the process’ amount of dynamic behavior.

  5. Mathematical modelling and linear stability analysis of laser fusion cutting

    Energy Technology Data Exchange (ETDEWEB)

    Hermanns, Torsten; Schulz, Wolfgang [RWTH Aachen University, Chair for Nonlinear Dynamics, Steinbachstr. 15, 52047 Aachen (Germany); Vossen, Georg [Niederrhein University of Applied Sciences, Chair for Applied Mathematics and Numerical Simulations, Reinarzstr.. 49, 47805 Krefeld (Germany); Thombansen, Ulrich [RWTH Aachen University, Chair for Laser Technology, Steinbachstr. 15, 52047 Aachen (Germany)

    2016-06-08

    A model for laser fusion cutting is presented and investigated by linear stability analysis in order to study the tendency for dynamic behavior and subsequent ripple formation. The result is a so called stability function that describes the correlation of the setting values of the process and the process’ amount of dynamic behavior.

  6. Array-level stability enhancement of 50 nm AlxOy ReRAM

    Science.gov (United States)

    Iwasaki, Tomoko Ogura; Ning, Sheyang; Yamazawa, Hiroki; Takeuchi, Ken

    2015-12-01

    ReRAM's low voltage and low current programmability are attractive features to solve the scaling issues of conventional floating gate Flash. However, read instability in ReRAM is a critical issue, due to random telegraph noise (RTN), sensitivity to disturb and retention. In this work, the array-level characteristics of read stability in 50 nm AlxOy ReRAM are investigated and a circuit technique to improve stability is proposed and evaluated. First, in order to quantitatively assess memory cell stability, a method of stability characterization is defined. Next, based on this methodology, a proposal to improve read stability, called ;stability check loop; is evaluated. The stability check loop is a stability verification procedure, by which, instability improvement of 7×, and read error rate improvement of 40% are obtained.

  7. The stability margin on EAST tokamak

    International Nuclear Information System (INIS)

    Jin-Ping, Qian; Bao-Nian, Wan; Biao, Shen; Bing-Jia, Xiao; Walker, M.L.; Humphreys, D.A.

    2009-01-01

    The experimental advanced superconducting tokamak (EAST) is the first full superconducting tokamak with a D-shaped cross-sectional plasma presently in operation. Its poloidal coils are relatively far from the plasma due to the necessary thermal isolation from the superconducting magnets, which leads to relatively weaker coupling between plasma and poloidal field. This may cause more difficulties in controlling the vertical instability by using the poloidal coils. The measured growth rates of vertical stability are compared with theoretical calculations, based on a rigid plasma model. Poloidal beta and internal inductance are varied to investigate their effects on the stability margin by changing the values of parameters α n and γ n (Howl et al 1992 Phys. Fluids B 4 1724), with plasma shape fixed to be a configuration with k = 1.9 and δ = 0.5. A number of ways of studying the stability margin are investigated. Among them, changing the values of parameters κ and l i is shown to be the most effective way to increase the stability margin. Finally, a guideline of stability margin M s (κ, l i , A) to a new discharge scenario showing whether plasmas can be stabilized is also presented in this paper

  8. A reduced order model of a quadruped walking system

    International Nuclear Information System (INIS)

    Sano, Akihito; Furusho, Junji; Naganuma, Nobuyuki

    1990-01-01

    Trot walking has recently been studied by several groups because of its stability and realizability. In the trot, diagonally opposed legs form pairs. While one pair of legs provides support, the other pair of legs swings forward in preparation for the next step. In this paper, we propose a reduced order model for the trot walking. The reduced order model is derived by using two dominant modes of the closed loop system in which the local feedback at each joint is implemented. It is shown by numerical examples that the obtained reduced order model can well approximate the original higher order model. (author)

  9. Nuclear-coupled thermal-hydraulic nonlinear stability analysis using a novel BWR reduced order model. Pt. 1. The effects of using drift flux versus homogeneous equilibrium models

    International Nuclear Information System (INIS)

    Dokhane, A.; Henning, D.; Chawla, R.; Rizwan-Uddin

    2003-01-01

    BWR stability analysis at PSI, as at other research centres, is usually carried out employing complex system codes. However, these do not allow a detailed investigation of the complete manifold of all possible solutions of the associated nonlinear differential equation set. A novel analytical, reduced order model for BWR stability has been developed at PSI, in several successive steps. In the first step, the thermal-hydraulic model was used for studying the thermal-hydraulic instabilities. A study was then conducted of the one-channel nuclear-coupled thermal-hydraulic dynamics in a BWR by adding a simple point kinetic model for neutron kinetics and a model for the fuel heat conduction dynamics. In this paper, a two-channel nuclear-coupled thermal-hydraulic model is introduced to simulate the out-of phase oscillations in a BWR. This model comprises three parts: spatial mode neutron kinetics with the fundamental and fist azimuthal modes; fuel heat conduction dynamics; and thermal-hydraulics model. This present model is an extension of the Karve et al. model i.e., a drift flux model is used instead of the homogeneous equilibrium model for two-phase flow, and lambda modes are used instead of the omega modes for the neutron kinetics. This two-channel model is employed in stability and bifurcation analyses, carried out using the bifurcation code BIFDD. The stability boundary (SB) and the nature of the Poincare-Andronov-Hopf bifurcation (PAF-B) are determined and visualized in a suitable two-dimensional parameter/state space. A comparative study of the homogeneous equilibrium model (HEM) and the drift flux model (DFM) is carried out to investigate the effects of the DFM parameters the void distribution parameter C 0 and the drift velocity V gi -on the SB, the nature of PAH bifurcation, and on the type of oscillation mode (in-phase or out-of-phase). (author)

  10. Experiments indicating a second hydrogen ordered phase of ice VI.

    Science.gov (United States)

    Gasser, Tobias M; Thoeny, Alexander V; Plaga, Lucie J; Köster, Karsten W; Etter, Martin; Böhmer, Roland; Loerting, Thomas

    2018-05-14

    In the last twelve years five new ice phases were experimentally prepared. Two of them are empty clathrate hydrates and three of them represent hydrogen ordered counterparts of previously known disordered ice phases. Here, we report on hydrogen ordering in ice VI samples produced by cooling at pressures up to 2.00 GPa. Based on results from calorimetry, dielectric relaxation spectroscopy, Raman spectroscopy, and powder X-ray diffraction the existence of a second hydrogen ordered polymorph related to ice VI is suggested. Powder X-ray data show the oxygen network to be the one of ice VI. For the 1.80 GPa sample the activation energy from dielectric spectroscopy is 45 kJ mol -1 , which is much larger than for the known hydrogen ordered proxy of ice VI, ice XV. Raman spectroscopy indicates the 1.80 GPa sample to be more ordered than ice XV. It is further distinct from ice XV in that it experiences hydrogen disordering above ≈103 K which is 26 K below the ice XV to ice VI disordering transition. Consequently, below 103 K it is thermodynamically more stable than ice XV, adding a stability region to the phase diagram of water. For the time being we suggest to call this new phase ice β-XV and to relabel it ice XVIII once its crystal structure is known.

  11. Output Feedback Fractional-Order Nonsingular Terminal Sliding Mode Control of Underwater Remotely Operated Vehicles

    Directory of Open Access Journals (Sweden)

    Yaoyao Wang

    2014-01-01

    Full Text Available For the 4-DOF (degrees of freedom trajectory tracking control problem of underwater remotely operated vehicles (ROVs in the presence of model uncertainties and external disturbances, a novel output feedback fractional-order nonsingular terminal sliding mode control (FO-NTSMC technique is introduced in light of the equivalent output injection sliding mode observer (SMO and TSMC principle and fractional calculus technology. The equivalent output injection SMO is applied to reconstruct the full states in finite time. Meanwhile, the FO-NTSMC algorithm, based on a new proposed fractional-order switching manifold, is designed to stabilize the tracking error to equilibrium points in finite time. The corresponding stability analysis of the closed-loop system is presented using the fractional-order version of the Lyapunov stability theory. Comparative numerical simulation results are presented and analyzed to demonstrate the effectiveness of the proposed method. Finally, it is noteworthy that the proposed output feedback FO-NTSMC technique can be used to control a broad range of nonlinear second-order dynamical systems in finite time.

  12. On the conditions of exponential stability in active disturbance rejection control based on singular perturbation analysis

    Science.gov (United States)

    Shao, S.; Gao, Z.

    2017-10-01

    Stability of active disturbance rejection control (ADRC) is analysed in the presence of unknown, nonlinear, and time-varying dynamics. In the framework of singular perturbations, the closed-loop error dynamics are semi-decoupled into a relatively slow subsystem (the feedback loop) and a relatively fast subsystem (the extended state observer), respectively. It is shown, analytically and geometrically, that there exists a unique exponential stable solution if the size of the initial observer error is sufficiently small, i.e. in the same order of the inverse of the observer bandwidth. The process of developing the uniformly asymptotic solution of the system reveals the condition on the stability of the ADRC and the relationship between the rate of change in the total disturbance and the size of the estimation error. The differentiability of the total disturbance is the only assumption made.

  13. European Security through EU-Russian Relations: Towards a New Multilateral Order?

    Directory of Open Access Journals (Sweden)

    Sandra Fernandes

    2011-05-01

    Full Text Available Since the end of the Cold War, the EU and Russia have managed to create an original framework for institutionalised cooperation despite asymmetric characteristics. Yet, the way these two main security actors interact has an impact on the (non-resolution of security issues in Europe, ranging from ‘‘frozen conflicts’’ to the discussion of the security architecture. Since the second mandate of President Putin, the relation has been characterised by two paradoxical features. On the one hand, the methodology and the domains of cooperation have reached a high degree of achievement. On the other hand, the political quality of the relationship has deteriorated and it is not able to achieve the desired ‘‘strategic partnership’’ that should be based on a common set of values and principles. This article aims to define multilateralism as a paradigm applicable to EU-Russian relations. It examines their relationship in the security and defence realm and the Union’s reactions to a new security approach by Russia since the 2008 Medvedev proposal. The article questions how the EU-Russian political dialogue impacts on multilateralism in the security field. The conclusion considers EU-Russian relations as a peculiar multilateral playground addressing common security challenges, which still needs to be developed further in order to be instrumental in the search for collective and legitimate solutions.

  14. The role of curing period on the engineering characteristics of a cement-stabilized soil

    Directory of Open Access Journals (Sweden)

    Athanasopoulou Antonia

    2016-07-01

    Full Text Available Very often, pavements constructed in an economical manner or matching surface elevations of adjacent lanes cannot be designed for the soil conditions of the existing subgrade. Therefore, there is a need to stabilize the soil with an appropriate chemical substance in order to increase its strength to a satisfactory level. For the enhancement of subgrade soil strength characteristics, lime and cement are the most commonly used stabilizers. An experimental program was directed to the evaluation of a clayey soil and its mixtures with different cement contents performing tests on the index properties, the moisture-density relation, the unconfined compressive strength, and linear shrinkage. There is a definite improvement in strength. The time interval used to cure the prepared specimens affected positively both strength and plasticity features of the mixtures. A comparison with mixtures of the same soil with lime has been made, because of the wide use of lime in clay soil stabilization projects.

  15. Thermodynamic Stability of Ice II and Its Hydrogen-Disordered Counterpart: Role of Zero-Point Energy.

    Science.gov (United States)

    Nakamura, Tatsuya; Matsumoto, Masakazu; Yagasaki, Takuma; Tanaka, Hideki

    2016-03-03

    We investigate why no hydrogen-disordered form of ice II has been found in nature despite the fact that most of hydrogen-ordered ices have hydrogen-disordered counterparts. The thermodynamic stability of a set of hydrogen-ordered ice II variants relative to ice II is evaluated theoretically. It is found that ice II is more stable than the disordered variants so generated as to satisfy the simple ice rule due to the lower zero-point energy as well as the pair interaction energy. The residual entropy of the disordered ice II phase gradually compensates the unfavorable free energy with increasing temperature. The crossover, however, occurs at a high temperature well above the melting point of ice III. Consequently, the hydrogen-disordered phase does not exist in nature. The thermodynamic stability of partially hydrogen-disordered ices is also scrutinized by examining the free-energy components of several variants obtained by systematic inversion of OH directions in ice II. The potential energy of one variant is lower than that of the ice II structure, but its Gibbs free energy is slightly higher than that of ice II due to the zero-point energy. The slight difference in the thermodynamic stability leaves the possibility of the partial hydrogen-disorder in real ice II.

  16. Research on differences and correlation between tensile, compression and flexural moduli of cement stabilized macadam

    Directory of Open Access Journals (Sweden)

    Yi Yang

    2017-07-01

    Full Text Available In order to reveal the differences and conversion relations between the tensile, compressive and flexural moduli of cement stabilized macadam, in this paper, we develop a new test method for measuring three moduli simultaneously. By using the materials testing system, we test three moduli of the cement stabilized macadam under different loading rates, propose a flexural modulus calculation formula which considers the shearing effect, reveal the change rules of the tensile, compression and flexural moduli with the loading rate and establish the conversion relationships between the three moduli. The results indicate that: three moduli become larger with the increase of the loading rate, showing a power function pattern; with the shear effect considered, the flexural modulus is increased by 47% approximately over that in the current test method; the tensile and compression moduli of cement stabilized macadam are significantly different. Therefore, if only the compression modulus is used as the structural design parameter of asphalt pavement, there will be a great deviation in the analysis of the load response. In order to achieve scientific design and calculation, the appropriate design parameters should be chosen based on the actual stress state at each point inside the pavement structure.

  17. Dynamics of Equilibrium Points in a Uniformly Rotating Second-Order and Degree Gravitational Field

    Science.gov (United States)

    Feng, Jinglang; Hou, Xiyun

    2017-07-01

    Using tools such as periodic orbits and invariant manifolds, the global dynamics around equilibrium points (EPs) in a rotating second-order and degree gravitational field are studied. For EPs on the long axis, planar and vertical periodic families are computed, and their stability properties are investigated. Invariant manifolds are also computed, and their relation to the first-order resonances is briefly discussed. For EPs on the short axis, planar and vertical periodic families are studied, with special emphasis on the genealogy of the planar periodic families. Our studies show that the global dynamics around EPs are highly similar to those around libration points in the circular restricted three-body problem, such as spatial halo orbits, invariant manifolds, and the genealogy of planar periodic families.

  18. Understanding chemical-potential-related transient pore-pressure response to improve real-time borehole (in)stability predictions

    Energy Technology Data Exchange (ETDEWEB)

    Tare, U.A.; Mody, F.K.; Mese, A.I. [Halliburton Energy Services, Cairo (Egypt)

    2000-11-01

    Experimental studies were conducted to explain the concept of a real-time wellbore (in)stability logging methodology. The role of the chemical potential of drilling fluids on transient pore pressure and time-dependent rock property alterations of shale formations was examined by providing details about a pore pressure transmission (PPT) test. The PPT experiments exposed formation (shale) cores under simulated downhole conditions to various salt solutions and drilling fluids. The main objective was to translate the results of the PPT tests to actual drilling conditions. A 20 per cent w/w calcium chloride solution was exposed to a Pierre II shale under high pressure in the PPT apparatus. The PPT test was used to estimate the impact of a drilling fluid on shale pore pressure. The efficiency of the salt solution/shale system was also estimated. Estimates of the dynamic rock properties were made based on the obtained acoustic data. It was determined that in order to accurately model time-dependent wellbore (in)stability in the field, it is important to calibrate representative shale core response to drilling fluids under realistic in-situ conditions. The 20 per cent w/w calcium chloride solution showed very low membrane efficiency of 4.45 per cent. It was concluded that changes in the shale dynamic rock properties as a function of test fluid exposure can be obtained from the simultaneous acquisition of sonic compression and shear wave velocity data. 12 refs., 5 figs.

  19. Stability of glassy hierarchical networks

    Science.gov (United States)

    Zamani, M.; Camargo-Forero, L.; Vicsek, T.

    2018-02-01

    The structure of interactions in most animal and human societies can be best represented by complex hierarchical networks. In order to maintain close-to-optimal function both stability and adaptability are necessary. Here we investigate the stability of hierarchical networks that emerge from the simulations of an organization type with an efficiency function reminiscent of the Hamiltonian of spin glasses. Using this quantitative approach we find a number of expected (from everyday observations) and highly non-trivial results for the obtained locally optimal networks, including, for example: (i) stability increases with growing efficiency and level of hierarchy; (ii) the same perturbation results in a larger change for more efficient states; (iii) networks with a lower level of hierarchy become more efficient after perturbation; (iv) due to the huge number of possible optimal states only a small fraction of them exhibit resilience and, finally, (v) ‘attacks’ targeting the nodes selectively (regarding their position in the hierarchy) can result in paradoxical outcomes.

  20. The influence of Ni additions on the relative stability of η and η′ Cu6Sn5

    KAUST Repository

    Schwingenschlö gl, Udo; Di Paola, Cono; Gourlay, C. M.; Nogita, K.

    2010-01-01

    We investigate how 5 at. % Ni influences the relative stability of η and η′ Cu6Sn5. Synchrotron x-ray diffraction shows that, while Cu6Sn5 exists as η′ at 25 and 150 °C and transforms to η on heating to 200 °C, Cu5.5Ni0.5Sn5 is best fit to η