multiple time scale dynamics with two fast variables and one slow ...

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Figure 4.2: Illustration of transversal intersection of stable and unstable manifolds of the slow manifolds W s (S l,ǫ) (green) and W u (S r,ǫ) (magenta). The manifolds are truncated at the yellow section Σ and the trajectoryγ f w∪γbw started onΣat the transversal intersection point xsu is shown in red. had to be truncated almost immediately after they entered a neighborhood of a slow manifold. The final output of the algorithm after interpolation near the truncation points is shown in Figure 4.4. Now we consider the case of “slow waves” and work with smaller wave speeds s. Homoclinic orbits representing slow waves should be thought of as perturbations of singular limit orbits for the FitzHugh-Nagumo equation (3.6) with s=0. In this case the fast subsystem x ′ 1 x ′ 2 = x2 = 1 5 (− f (x1)+y− p) (4.9) is Hamiltonian. Singular homoclinic orbits exist in a single fast subsystem with the y-coordinate of the equilibrium y= x∗ 1 . A direct application of Fenichel the- 109
y 0.15 0.1 0.05 0 −0.05 ε=0.001, p=0, s=1.2463 −0.1 0 x 0.1−0.2 0 0.2 0.4 0.6 0.8 1 2 x 1 0.2 0.1 0 −0.1 0.1 0.05 0 ε=0.001, p=0, s=1.2463 Figure 4.3: Illustration of the algorithm for computing homoclinic orbits in the FitzHugh-Nagumo equation. (a)Slow manifolds S l,ǫ and S r,ǫ are shown in black and the unstable manifold of the equilibrium W u (q) is displayed in red. (b) Pieces of the homoclinic orbit; slow segments in black, fast segments in red and S shown in blue. y 0.15 0.1 0.05 0 0.06 0.04 0.02 0 y ε=0.001, p=0, s=1.2463 −0.02 x 2 −0.04 Figure 4.4: Homoclinic orbit (green) of the FitzHugh-Nagumo equation representing a fast wave. The equilibrium point q is shown in red. 110 −0.06 x 2 0 −0.05 0.2 −0.1 x 1 0.4 0 0.6 0.2 x 1 0.4 0.6 0.8
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MULTIPLE TIME SCALE DYNAMICS WITH T
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MULTIPLE TIME SCALE DYNAMICS WITH T
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To my family. iv
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ing mechanical systems.”, [E.T. P
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TABLE OF CONTENTS Biographical Sket
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LIST OF TABLES 5.1 Euclidean distan
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3.1 Bifurcation diagram of (3.6). H
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4.6 Boundary conditions are blue an
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6.3 For all computations of the ful
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where (x, y)∈R m × R n are varia
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the general definition of normal hy
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fast-slow system and yields: ˙x=(D
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whereΛ,Γare matrix-valued functio
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forǫ> 0. Therefore they have no im
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The Hopf bifurcation is supercritic
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where the algorithm can be used to
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slow flow. In particular the manifo
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f ast whereφ t is the flow of the
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whereµ∈R p are parameters. Usual
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We shall not prove this result but
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d as given in equation (2.5). Let p
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variables x1= u, x2= v and y=w we g
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The geometry of the system for one
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(0, 0, 0). 2.3 The Exchange Lemma I
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withδ>0 sufficiently small. The sa
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Theorem 2.3.2. Let ¯q ∈ M∩{|a|
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exit point of a trajectory starting
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Hence we have k=1=l and n=2 in view
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The variational equations describin
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(iii) Denote byη1i the i-th row of
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Then let H(Z, X, t) := X ′ − BX
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Proof. First, we work near q, then|
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This result can be written more com
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Proof. (of Theorem 2.4.2) The argum
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ˆZ is still exponentially small. P
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in the FitzHugh-Nagumo equation ǫ
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center-unstable manifold W cu (0, 0
Page 75 and 76: where the second “fast jump” oc
Page 77 and 78: CHAPTER 3 PAPER I: “HOMOCLINIC OR
Page 79 and 80: [39, 40, 41, 42]). It states that f
Page 81 and 82: papers. Geometric singular perturba
Page 83 and 84: s 2.2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0
Page 85 and 86: One can view this as a projection o
Page 87 and 88: for x1. We find that there are thre
Page 89 and 90: We compute the functionsγl andγr
Page 91 and 92: 3.3.3 Two Slow Variables, One Fast
Page 93 and 94: Also recall that the y-nullcline pa
Page 95 and 96: is negative for all values h∈(0,
Page 97 and 98: 3.4 The Full System 3.4.1 Hopf Bifu
Page 99 and 100: check whether this observation of a
Page 101 and 102: indistinguishable numerically from
Page 103 and 104: we should view this curve as an app
Page 105 and 106: s 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 sin
Page 107 and 108: waves” (see e.g. [63, 15, 69]). 3
Page 109 and 110: the singular limits but it cannot b
Page 111 and 112: Then (3.24) transforms to a three t
Page 113 and 114: with x∈R m the vector of fast var
Page 115 and 116: ons that was used by David Terman i
Page 117 and 118: 0.15 0.1 0.05 0 −0.05 0.15 0.1 0.
Page 119 and 120: from the input data. (If b−a is a
Page 121 and 122: This explicit solution provides a b
Page 123 and 124: 4.4.2 Traveling Waves of the FitzHu
Page 125: computing the homoclinic orbit, eve
Page 129 and 130: eturns directly to q. Figure 4.5(b)
Page 131 and 132: are complicated [107]: we expect th
Page 133 and 134: t∈[0, 1]: z ′ = T F(z) H0(z(0))
Page 135 and 136: CHAPTER 5 PAPER III: “HOMOCLINIC
Page 137 and 138: s 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 H
Page 139 and 140: For a point p∈C0 we say that C0 i
Page 141 and 142: conjugate pair of eigenvalues for t
Page 143 and 144: Proof. (Sketch) The Lyapunov coeffi
Page 145 and 146: Table 5.1: Euclidean distance in (p
Page 147 and 148: gency of W s (q) with E u (Cl,ǫ).
Page 149 and 150: y x2 W s (q) C0 Cl,ǫ x1 W s (Cl,ǫ
Page 151 and 152: periodic orbit and q are restricted
Page 153 and 154: yΣ1=ψ(Σ1) andΣ2=ψ(Σ2); see Fi
Page 155 and 156: eigenvalues, Shilnikov [102] proved
Page 157 and 158: s 1.39 1.385 1.38 1.375 1.37 1.365
Page 159 and 160: Figure 5.9(a)-(b). It was obtained
Page 161 and 162: was carried out with the stiff solv
Page 163 and 164: 6.2 Introduction Our framework in t
Page 165 and 166: are called fold points. We can use
Page 167 and 168: curve C= Cl∪{(0, 0)}∪ Cr where
Page 169 and 170: explicitly. Note that currently no
Page 171 and 172: A slight modification of the formul
Page 173 and 174: 6.5 Relating l1 and K Krupa and Szm
Page 175 and 176: nates. The computer algebra system
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atλ=λH= 0 forǫ= 0.05 is l MC 1
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imum and maximum of the cubic. The
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6.8 Additions It is important to no
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−7.85 −7.95 −8.05 λ x −7.9
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BIBLIOGRAPHY [1] V.I. Arnold. Encyc
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[26] M. Desroches, B. Krauskopf, an
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icated to Floris Takens. Eds.: Henk
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[74] T.J. Kaper and C.K.R.T. Jones.
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[98] H.G. Rotstein, M. Wechselberge
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