中文摘要：

在一个 semi-discretized Euler-Bernoulli 横梁方程，非近的附近的相互作用和为波浪繁殖的时间的规模的大跨度为人工的边界处理提出挑战到有效性和稳定性。与与一个三原子的潜力认为是一个原子格子的分离方程，二个精确人工的边界条件首先这里被导出。思考系数和数字测试说明建议方法的能力。特别地，时间历史处理给一个准确边界条件，还与到数字实现的敏感。ALEX (几乎准确) 边界状况是数字地更有效。

英文摘要：

In a semi-discretized Euler-Bernoulli beam equa- tion, the non-nearest neighboring interaction and large span of temporal scales for wave propagations pose challenges to the effectiveness and stability for artificial boundary treat- ments. With the discrete equation regarded as an atomic lattice with a three-atom potential, two accurate artificial boundary conditions are first derived here. Reflection co- efficient and numerical tests illustrate the capability of the proposed methods. In particular, the time history treatment gives an exact boundary condition, yet with sensitivity to nu- merical implementations. The ALEX （almost EXact） bound- ary condition is numerically more effective.