Combined effects of homogenization and singular perturbations: Quantitative estimates

We investigate quantitative estimates in periodic homogenization of second-order elliptic systems of elasticity with singular fourth-order perturbations. The convergence rates, which depend on the scale κ that represents the strength of the singular perturbation and on the length scale ε of the heterogeneities, are established. We also obtain the large-scale Lipschitz estimate, down to the scale ε and independent of κ. This large-scale estimate, when combined with small-scale estimates, yields the classical Lipschitz estimate that is uniform in both ε and κ.

Aubry-Mather type at the Double Resonance

This chapter proves Aubry-Mather type for the double resonance regime. It begins by considering the “non-critical energy case” and showing that the cohomologies as chosen are of Aubry-Mather type. The proof consists of two cases. In the first case, the chapter uses the almost verticality of the cylinder, and the idea is similar to the proof of Theorem 9.3. It applies the a priori Lipschitz estimates for the Aubry sets. In the second case, the chapter uses the strong Lipschitz estimate for the energy, and the idea is similar to the proof of Theorem 11.1. It then looks at the construction of the local coordinates. This is done separately near the hyperbolic fixed point (local) and away from it (global).

Convergence of an implicit scheme for diagonal non-conservative hyperbolic systems

In this paper, we consider diagonal non-conservative hyperbolic systems in one space dimension with monotone and large Lipschitz continuous data. Under a certain nonnegativity condition on the Jacobian matrix of the velocity of the system, global existence and uniqueness results of a Lipschitz solution for this system, which is not necessarily strictly hyperbolic, was already proven. We propose a natural implicit scheme satisfiying a similar Lipschitz estimate at the discrete level. This property allows us to prove the convergence of the scheme without assuming it strictly hyperbolic.

On the spreading of characteristics for non-convex conservation laws

We study the spreading of characteristics for a class of one-dimensional scalar conservation laws for which the flux function has one point of inflection. It is well known that in the convex case the characteristic speed satisfies a one-sided Lipschitz estimate. Using Dafermos' theory of generalized characteristics, we show that the characteristic speed in the non-convex case satisfies an Hölder estimate. In addition, we give a one-sided Lipschitz estimate with an error term given by the decrease of the total variation of the solution.