伽玛射线测量径流泥沙含量算法中质量吸收系数优选及其对测量误差影响的分析

Optimal choice of mass absorption coefficient and analysis of its influence on measured error in algorithm of using gamma ray to measure runoff sediment concentration

质量吸收系数是伽玛射线测量径流泥沙含量理论计算公式中由伽玛射线记数率确定泥沙含量的基本参数。该文研究了确定质量吸收系数的多点法和单点法。在多点法中 ,提出了确定质量吸收系数的回归方法 ,推导了由大量 (多点 )试验数据计算质量吸收系数的回归公式。采用大量实测数据由回归公式确定的质量吸收系数准确且精度较高 ,能在很大程度上消除随机误差的影响。而单点法通过几个特殊的取值点 (单点 )来估算质量吸收系数 ,具有参数确定快速、物理概念明确的优点。另外 ,该文从理论上分析了质量吸收系数变化对泥沙含量测量精度的影响 ,结果表明质量吸收系数的相对变化与泥沙含量的相对变化成正比例关系 ,且比例系数为 1。从而确定了两种方法的有效性、优缺点和应用方法。

The mass absorption coefficient is the basic parameter to determine sediment concentration by gamma ray count ratio in the theoretical computing formula of using gamma ray to measure the runoff sediment concentration. In this paper, a single point method and a multi point method are studied to determine the mass absorption coefficient. As for the multi point method, the regression method to determine the mass absorption coefficient is presented and the regression formula is derived to compute the mass absorbing coefficient using a large number of (multiple points) experimental data. The mass absorption coefficient that makes use of a great deal of measured experimental data to determine the mass absorption coefficient by the regression formula has very high precision and can get rid of the effects of the stochastic errors. However, the single point method can determine the parameter quickly and has specific physical concept because it estimates the mass absorption coefficient by several special points. In addition, the influence of the change of the mass absorption coefficient on the measurement precision of the sediment concentration is analyzed theoretically and it shows that there is direct proportional relationship between the relative change of the mass absorption coefficient and that of the sediment concentration, and the proportion coefficient is 1. Therefore the validity, the advantage, disadvantage and application method of these two methods are determined.