In qualitative theory of differential equations, an important role is played by special classes of solutions, like periodic solutions or solutions to some boundary value problems. When a system of ordinary differential equations has equilibria, i.e. co
Préface vii
Avant-propos xi
Liste des publications lix
A Study of Heteroclinic Orbits for a Class of Fourth Order Ordinary Differential Equations 1
Contents 3
Introduction 5
An overview 7
Methods 7
The Model Equation 8
The Variational Approach 12
General Framework 14
Outline of the Thesis 16
Minimization Methods and Second Order Systems 16
Minimization of Positive Functionals 17
Sign Changing Lagrangians 20
Multi-transition Heteroclinics 22
Connections between Non-consecutive Equilibria 24
Open Questions 26
About the Presentation 26
Chapter 1. The VariationalMethods and Heteroclinics for Second Order
Equations and Systems 27
1.1. The Variational Methods 27
1.2. Basic Arguments for Scalar Equations 33
1.2.1. Phase Plane Analysis 33
1.2.2. The Autonomous Case 34
1.2.3. The Periodic Case 38
1.2.4. The Bounded Case 41
1.3. Reversible Hamiltonian Systems 43
1.4. Periodic Hamiltonian Systems: Heteroclinic Chains 50
1.5. Notes and Comments 56
Chapter 2. Minimization of Positive Functionals 61
2.1. The Extended Fisher-Kolmogorov Equation 62
2.2. Double-well Potentials with Degenerate Minima 67
2.2.1. Proof of Proposition 2.9 73
2.3. Qualitative Properties of the Minimizers 78
2.3.1. Clipping 79
2.3.2. Monotonicity of the Transitions 81
2.3.3. Oscillations in the Tails 83
2.3.4. Symmetric Functionals in the Saddle-foci Case 87
2.4. Notes and Comments 87
Chapter 3. Sign Changing Lagrangians 91
3.1. Functionals with Sign Changing Acceleration Coefficient 92
3.2. Functionals of Swift-Hohenberg Type 97
3.3. Non-symmetric Functionals 103
3.3.1. Analysis of the Local Minimizers Close to a Saddle-focus Equilibrium 104
3.3.2. Existence of a Minimizer 107
3.4. Notes and Comments 114
Chapter 4. Multi-transition Connections 117
4.1. Homotopy Classes of Heteroclinic Solutions 117
4.2. Multi-transition Heteroclinics 119
4.2.1. Functionals of Swift-Hohenberg Type 120
4.2.2. Sign Changing Acceleration Coefficient 132
4.3. Multi-transition Homoclinics 135
4.4. Notes and Comments 137
Chapter 5. A Ginzburg-Landau Model for Ternary Mixtures:
Connections Between Non-consecutive Equilibria 141
5.1. A Ginzburg-Landau Model for Ternary Mixtures 141
5.1.1. Binary Fluids 141
5.1.2. Ternary Mixtures 142
5.2. The Fourth Order Model 143
5.4. Notes and Comments 147
Bibliography 149
List of Figures 155
Index 157