Formulation of Various Boundary Conditions Based on the D'Alembert Solution of the One-Dimensional Wave Equation

In this paper, we first present an overview of Da'lembert's solution and impedance boundary conditions, and then outline the excitation boundary conditions, including stick-slip vibration of a string and an excitation model of an expansion part of an acoustic self-excited phenomenon with a heat source. After that, we summarize the reflection law of a rigid wall from the viewpoint of the law of conservation of energy, and then introduce the process of examining the reflection law of the end when the string length changes.