共查询到20条相似文献,搜索用时 31 毫秒
1.
I.L. CaldasR.L. Viana J.D. Szezech Jr.J.S.E. Portela J. FonsecaM. Roberto C.G.L. MartinsE.J. da Silva 《Communications in Nonlinear Science & Numerical Simulation》2012,17(5):2021-2030
We review symplectic nontwist maps that we have introduced to describe Lagrangian transport properties in magnetically confined plasmas in tokamaks. These nontwist maps are suitable to describe the formation and destruction of transport barriers in the shearless region (i.e., near the curve where the twist condition does not hold). The maps can be used to investigate two kinds of problems in plasmas with non-monotonic field profiles: the first is the chaotic magnetic field line transport in plasmas with external resonant perturbations. The second problem is the chaotic particle drift motion caused by electrostatic drift waves. The presented analytical maps, derived from plasma models with equilibrium field profiles and control parameters that are commonly measured in plasma discharges, can be used to investigate long-term transport properties. 相似文献
2.
Robert J. Sacker 《Journal of Difference Equations and Applications》2013,19(1):89-92
We investigate the boundedness character of non-negative solutions of the rational system as in the title. We establish easily verifiable necessary and sufficient conditions, explicitly stated in terms of the parameters of the system, which determine the boundedness character of the system. 相似文献
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Paulo Brandão 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2018,35(5):1409-1433
We study the non-wandering set of contracting Lorenz maps. We show that if such a map f doesn't have any attracting periodic orbit, then there is a unique topological attractor. Furthermore, we classify the possible kinds of attractors that may occur. 相似文献
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Let be the standard closed positive cone in and let be the set of integers for which there exists a continuous, order preserving, subhomogeneous map , which has a periodic point with period . It has been shown by Akian, Gaubert, Lemmens, and Nussbaum that is contained in the set consisting of those for which there exist integers and such that , , and for some . This note shows that for all .
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We consider smooth multimodal maps which have finitely many non-flat critical points. We prove the existence of real bounds. From this we obtain a new proof for the non-existence of wandering intervals, derive extremely useful improved Koebe principles, show that high iterates have `negative Schwarzian derivative' and give results on ergodic properties of the map. One of the main complications in the proofs is that we allow to have inflection points.
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Pawe Goldstein Pawe Strzelecki Anna Zatorska-Goldstein 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2009,26(4):1387-1405
We prove that every polyharmonic map u∈Wm,2(Bn,SN−1) is smooth in the critical dimension n=2m. Moreover, in every dimension n , a weak limit u∈Wm,2(Bn,SN−1) of a sequence of polyharmonic maps uj∈Wm,2(Bn,SN−1) is also polyharmonic. 相似文献
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One may ask which maps between Hilbert modules allow for a completely positive extension to a map acting block-wise between the associated (extended) linking algebras. In these notes we investigate in particular those CP-extendable maps where the 22-corner of the extension can be chosen to be a homomorphism, the CP-H-extendable maps. We show that they coincide with the maps considered by Asadi [4], by Bhat, Ramesh, and Sumesh [9], and by Skeide [28]. We also give an intrinsic characterization that generalizes the characterization by Abbaspour Tabadkan and Skeide [1] of homomorphically extendable maps as those which are ternary homomorphisms. For general strictly CP-extendable maps we give a factorization theorem that generalizes those of Asadi, of Bhat, Ramesh, and Sumesh, and of Skeide for CP-H-extendable maps. This theorem may be viewed as a unification of the representation theory of the algebra of adjointable operators and the KSGNS-construction. Then, we examine semigroups of CP-H-extendable maps, so-called CPH-semigroups. As an application, we illustrate their relation with a new sort of generalized dilation of CP-semigroups, CPH-dilations. 相似文献
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In this paper we develop the notion of contact orders for pairs of continuous self-maps (f, g) from ℝn, showing that the set Con(f, g) of all possible contact orders between f and g is a topological invariant (we remark that Con(f, id) = Per(f)). As an interesting application of this concept, we give sufficient conditions for the graphs of two continuous self-maps
from ℝ intersect each other. We also determine the ordering of the sets Con(f, 0) and Con(f, h), for h ∈ Hom(ℝ) such that f ∘ h = h ∘ f. For this latter set we obtain a generalization of Sharkovsky’s theorem. 相似文献
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《Communications in Nonlinear Science & Numerical Simulation》2014,19(9):3119-3127
In this paper we introduce an algorithm which allows us to compute the topological entropy of a class of piecewise monotone continuous interval maps. The algorithm can be applied to a class of economic models called duopolies, and it can be useful to compute the topological entropy of periodic sequences of continuous maps which have been used in some population growth models. 相似文献
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Zhang Guangyuan 《中国科学A辑(英文版)》2001,44(3):330-337
Let Δυ be the unit ball in ℂυ with center 0 (the origin of υ) and let F:Δυ→ℂυbe a holomorphic map withF(0) = 0. This paper is to study the fixed point multiplicities at the origin 0 of the iteratesF
i
=F∘⋯∘F (i times),i = 1,2,.... This problem is easy when υ = 1, but it is very complicated when υ > 1. We will study this problem generally. 相似文献
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Jian Cheng 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2004,55(3):400-419
We study in this article the topological entropy of billiard systems on a convex domain
of the Euclidean plane. We restrict our attention to those systems whose boundary curve has
positive curvature and show that for generic billiard ball systems satisfying this condition the
topological entropy is positive. 相似文献
15.
Baruch Solel 《Journal of Functional Analysis》2006,235(2):593-618
We prove that every pair of commuting CP maps on a von Neumann algebra M can be dilated to a commuting pair of endomorphisms (on a larger von Neumann algebra). To achieve this, we first prove that every completely contractive representation of a product system of C∗-correspondences over the semigroup N2 can be dilated to an isometric (or Toeplitz) representation. 相似文献
16.
P. De Maesschalck 《Journal of Differential Equations》2008,244(6):1448-1466
This paper deals with the smoothness of the transition map between two sections transverse to the fast flow of a singularly perturbed vector field (one fast, multiple slow directions). Orbits connecting both sections are canard orbits, i.e. they first move rapidly towards the attracting part of a critical surface, then travel a distance near this critical surface, even beyond the point where the orbit enters the repelling part of the critical surface, and finally repel away from the surface. We prove that the transition map is smooth. In a transcritical situation however, where orbits from an attracting part of one critical manifold follow the repelling part of another critical manifold, the smoothness of the transition map may be limited, due to resonance phenomena that are revealed by blowing up the turning point! We present a polynomial example in R3. 相似文献
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A. Haro 《Journal of Differential Equations》2006,228(2):530-579
In this paper we prove rigorous results on persistence of invariant tori and their whiskers. The proofs are based on the parameterization method of [X. Cabré, E. Fontich, R. de la Llave, The parameterization method for invariant manifolds. I. Manifolds associated to non-resonant subspaces, Indiana Univ. Math. J. 52 (2) (2003) 283-328; X. Cabré, E. Fontich, R. de la Llave, The parameterization method for invariant manifolds. II. Regularity with respect to parameters, Indiana Univ. Math. J. 52 (2) (2003) 329-360]. The invariant manifolds results proved here include as particular cases of the usual (strong) stable and (strong) unstable manifolds, but also include other non-resonant manifolds. The method lends itself to numerical implementations whose analysis and implementation is studied in [A. Haro, R. de la Llave, A parameterization method for the computation of invariant tori and their whiskers in quasi-periodic maps: Numerical algorithms, preprint, 2005; A. Haro, R. de la Llave, A parameterization method for the computation of invariant tori and their whiskers in quasi-periodic maps: Numerical implementation and examples, preprint, 2005]. The results are stated as a posteriori results. Namely, that if one has an approximate solution which is not degenerate, then, one has a true solution not too far from the approximate one. This can be used to validate the results of numerical computations. 相似文献
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Aslı Deniz 《Journal of Difference Equations and Applications》2013,19(12):1627-1640
In this article, we present a landing theorem for periodic dynamic rays for transcendental entire maps which have bounded post-singular sets, by using standard hyperbolic geometry results. 相似文献