| 摘要 |
A method of determining the concentration of incombustible material in a predetermined volume of coal includes irradiating the volume with gamma -rays from a first source having a first, low energy; and simultaneously irradiating the volume with gamma -rays from a second source having a second, higher energy. Rays of back-scattered radiation from the irradiated volume are detected. An analogue signal for each ray that is detected is generated, an amplitude of said signal being representative of the energy of the ray. Each analogue signal is converted into an equivalent digital signal. For all values of signals in a predetermined range, the number of digital signals having the same value that are detected in a predetermined time period is determined and said signals of the same value are stored together to provide a frequency spectrum. The frequency spectrum is processed to provide the concentration of incombustible material in the volume. |
