研究有限矩形区域内，粒子运动到区域边界时会与区域边界发生不同作用（弹性碰撞和吸收两种可能的情况）下的布朗运动。-Finite rectangular region of the particle motion to the regional boundaries will occur with the different roles of the regional boundary (elastic collision and absorption of two possible scenarios), the Brownian motion.