Constrained Hamilton-Jacobi Equations and Further Applications Via Optimal Control Theory PDF Download

Author: Yeon Eung Kim
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Languages : en
Pages : 0

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Book Description
In this dissertation, two research directions are presented. The first direction is on the study of the constrained Hamilton-Jacobi equation \begin{equation*} \begin{cases} u_t=H(Du)+R(x, I(t)) & \text{in }\R^n \times (0,\infty), \\ \sup_{\R^n} u(\cdot, t)=0 & \text{on }[0,\infty), \end{cases} \end{equation*} with initial conditions $I(0)=I_0>0$, $u(x,0)=u_0(x)$ on $\R^n$. Here $(u, I)$ is a pair of unknowns and a Hamiltonian $H$ and a reaction term $R$ are given. Moreover, $I(t)$ is an unknown constraint (Lagrange multiplier) that constrains the supremum of $u$ to be always zero. We construct a solution in the viscosity setting using the fixed point argument when the reaction term $R(x, I)$ is strictly decreasing in $I$. We also discuss both uniqueness and nonuniqueness. For uniqueness, a certain structural assumption on $R(x, I)$ is needed. We also provide an example with infinitely many solutions when the reaction term is not strictly decreasing in $I$. Furthermore, the uniqueness of a pair $(u, I)$ is achieved for one-dimensional case using the optimal control formula. The second direction is based on joint work with H. Tran and S. Tu is concerned with rate of convergence of viscosity solutions to state-constraint Hamilton-Jacobi equations defined in nested domains. In particular, we consider a sequence of balls $\{ B_k\}_{k \in \N}$ in $\R^n$ for the domain where a ball centered at the origin with radius $k$ is denoted by $B_k$. We obtain rate of convergence of $u_k$ which is a solution to the state-constraint problem in $B_k$, to $u$ which is a solution to the corresponding problem in $\R^n$ using the optimal control formula. The rate we obtain is indeed optimal.