25,784 research outputs found
Self-exciting Faraday disk homopolar dynamos
No full textIn this paper we present an overview of recently published work on the Faraday disk self-exciting homopolar dynamos. We also extend the analysis of two such coupled self-exciting disk dynamos with linear series motors [Moroz et al., 1998a; Moroz et al., 1998b] to the situation where one or both dynamo subunits incorporate nonlinear motors. We examine the differences in some of the bifurcation transition sequences between the various cases and consider whether the nonlinear quenching of oscillatory solutions can occur [Hide, 1998]
Unstable periodic orbits in a four-dimensional Faraday disk dynamo
No full textIn this article, we return to a four-dimensional model for a self-exciting Faraday disk dynamo, originally investigated by Hide and Moroz [Hide, R. and Moroz, I.M., Effects due to induced azimuthal eddy currents in the self-exciting Faraday disk homopolar dynamo with a nonlinear series motor: I two special cases. Physica D 1999, 134, 387-301]. We extract unstable periodic orbits from long time series of chaotic trajectories by the method of close returns to a Poincaré section. We then employ recently developed topological tools to characterise the underlying chaotic attractor of the dynamo by identifying its branched manifold or template. © 2011 Taylor and Francis
The Malkus-robbins dynamo with a Nonlinear Series Motor.
No full textIn a recent paper Moroz [2003] considered a simplified version of third class self-exciting Faraday-disk dynamo model, introduced by Hide [1997], in the limit in which leads to the Malkus -Robbing dynamo [Malkus, 1972; Robbins, 1977] as a special case. In that study a linear series motor was incorporated which led to an enriching range of possible behavior that the original Malkus-Robbins dynamo could support. In this paper, we replace the linear motor by a nonlinear motor and consider the consequences on the dynamics of the dynamo
On the Behavior of a Self-Exciting Faraday Disk homopolar dynamo with a Variable Nonlinear Series Motor.
No full textIn this paper we seek to bridge the gap between the study of a self-exciting Faraday disk homopolar dynamo with a linear series motor [Hide et al., 1996] and the case when the torque acting on the armature of the motor is proportional to the square of the current flowing through the dynamo [Hide, 1998]. We also focus on the issue of when the nonlinear quenching of oscillatory solutions can occur. The present study is a special case of the more general problem when azimuthal eddy currents are permitted to flow [Moroz and Hide, 2000] and shares with that problem the existence of multiple steady states and Hopf bifurcations. This results in distinct double-zero bifurcations for the trivial and the nontrivial equilibrium states as well as other codimension-two bifurcations, which leads to the suppression of oscillatory solutions
Reply to "Comment on 'Ensemble Kalman filter with the unscented transform'"
No full textThis is a reply to the comment of Dr Sakov on the work "Ensemble Kalman filter with the unscented transform" of Luo and Moroz (2009)
Template analysis of the hide, skeldon, acheson dynamo
No full textSelf-exciting dynamos are nonlinear electro-mechanical engineering devices, or naturally-occurring magnetohydrodynamic fluid systems that convert mechanical energy into magnetic energy without the help of permanent magnets. Hide et al. [1] introduced a nonlinear system of three coupled ordinary differential equations to model a self-exciting Faraday disk homopolar dynamo. Since only a small selection of possible behaviours, including two examples of chaotic behaviour, was investigated by them, Moroz [2]performed a more extensive analysis of the dynamo model, including producing bifurcation transition diagrams and generating unstable periodic orbits for the two chaotic examples. We now extend that analysis and use ideas from topology [3] and results from a corresponding analysis of the Lorenz attractor to identify a possible template for the HSA dynamo. ©2008 Springer-Verlag Berlin Heidelberg
An analytical approach to the Schrodinger-Newton equations
No full textIn this paper we present the second part of a study of spherically-symmetric solutions of the Schrödinger-Newton equations for a single particle (Penrose R 1998 Quantum computation, entanglement and state reduction Phil. Trans. R. Soc. 356 1-13). We show that there exists an infinite family of normalizable, finite energy solutions which are characterized by being smooth and bounded for all values of the radial coordinate. We therefore provide analytical support for our earlier numerical integrations (Moroz I M et al 1998 Spherically-symmetric solutions of the Schrödinger-Newton equations Classical and Quantum Gravity 1998 15 2733-42)
Effects due to induced azimuthal eddy currents in a self-exciting Faraday disk homopolar dynamo with a nonlinear series motor: II. The general case
No full textThis paper forms the second part of a two-part study into the effects of azimuthal eddy currents in the Faraday disk self-exciting homopolar dynamo, connected in series with the coil when the applied couple driving the disk is steady. The Lorentz couple driving the armature of the motor is a general quadratic function I(1 - ε + εSI) of the current I(t), where 0 ≤ ε ≤ 1. Here we investigate how cases with 0 < ε < 1 relate to the two special cases of ε = 0 and ε = 1, considered in Part I of our study [Hide and Moroz, 1999]. One key difference is that the lack of reflectional symmetry in the general ε problem means that the linear stability curves for the onset of both steady and oscillatory behavior for both the trivial and the nontrivial equilibrium solutions no longer coincide. This results in distinct Takens-Bogdanov double-zero bifurcations for these states, as well as multiple branches to the Hopf bifurcation curves, associated with bifurcations from the nontrivial equilibrium states. Multiple bifurcations involving simultaneous steady and nondegenerate oscillatory solutions are also possible
Synchronized chaos in coupled double disk homopolar dynamos
No full textSymmetrically coupled systems of N self-exciting Faraday disk homopolar dynamos have been proposed by Hide [1997] as a testbed for both the analytical and numerical study of the dynamics of coupled dynamo systems. There arises a natural hierarchy of systems, consisting of a series of N single disk dynamos, each in series with a motor [Hide et al., 1996]. Synchronization in the dynamics of these systems is investigated. The transition from the special case of strict amplitude and linear phase locking to the case of more general synchronization is examined. The particular case of two magnetically coupled homopolar dynamos with dissimilar characteristics is considered; the behavior of this N = 2 case is governed by six-coupled nonlinear ordinary differential equations which contain a total of thirteen dimensionless parameters. It is proved that for sufficiently small perturbations, the states of each of the two component dynamos are locked together. Numerical results suggest that this locking extends to finite perturbations, the state of one system being a linear function of the state of the other. As the size of the perturbation increases, this strict phase locking is lost, yet the complicated chaotic trajectories of each dynamo appear to remain strictly synchronized. This paper is therefore the result of a previous study of coupled dynamos [Moroz et al., 1998] in which no more than five of the parameters were assumed to be independent
El feminismo de Estado en España: El Instituto de la Mujer, 1983-1994
No full textEste trabajo contiene un análisis del Instituto de la Mujer (IM), el principal organismo público de igualdad de la Administración central en España. Al igual que las instituciones feministas de otros países, el IM fue establecido con el propósito de impulsar el establecimiento de políticas que contribuyeran a mejorar la posición de las mujeres en la sociedad. La primera parte del artículo examina el proceso de creación del IM, prestando especial atención al papel desempeñado por el movimiento asociativo de mujeres, así como a la importancia de las influencias internacionales. Se estudian además las principales características formales de la institución. La segunda parte contiene una evaluación (provisional) del impacto del IM en la formulación y puesta en práctica de las políticas de igualdad. Por último, se examinan el carácter y las consecuencias de las relaciones formales e informales existentes entre los miembros del movimiento feminista y del feminismo institucional.Publicad
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