Chapter 1 Introduction 1.1 Models 1.2 Main Results Chapter 2 Optimal Time Decay Rates of Two-phase Flow 2.1 Preliminaries 2.2 The Spectral Analysis of Linearized System 2.3 Global Existence and Nonlinear Time Decay Rates Chapter 3 Pointwise Behaviors of the Compressible MHD in a Half Line 3.1 Preliminaries 3.2 The Global Existence of Classical Solutions to the IBVP 3.3 The Estimates of Green's Function to the IBVP 3.4 Nonlinear Pointwise Estimates Chapter 4 Asymptotic Behavior of Linearized Boltzmann Equation for Soft Potentials With Cut-off 4.1 Preliminaries 4.2 Spectrum and Resolvent 4.3 Time Decay Estimates of Semigroup References