The theory of medical microtron is introduced.The theory of medical runway microtron is expressed and its characteristics are compared with electron linear accelerator.

着重了回旋加速器原理，重了跑道式回旋加速器的作原理，并对回旋加速器直线加速器的特进行了比较。

Counterfort retaining walls are optimized in the paper, using the optimum program, costs of different counterfort retaining wall parameters were calculated and based on the contrast analysis.

本文对扶壁式挡土墙进行优化计算,利用优化设计程序对不同参数下的截面状态程造价进行分析比较。