声层析成像仓储粮食温度监测方法

Temperature monitoring method for stored grain based on acoustic tomography

为了更及时地发现仓储粮食中存在的热点,提出了声层析成像仓储粮食温度监测方法.推导了粮食中声波传播时间与粮食温度的函数关系,定义声速转换因子,将粮食中的测量声速转换成相同温度、相同气体自由空间中的声速,建立了声学法储粮温度测量模型.分析了声速转换因子的影响因素及应对措施,开发了基于虚拟仪器的声层析成像温度监测实验系统.以大豆填充实验粮仓,对系统各声波路径的实测声速分布规律进行研究并提出修正转换方法,对电加热器形成的三种粮食温度分布进行了重建实验.结果表明,重建图像能够清晰地反映大豆中的热点位置和热点温度.因此,声层析成像仓储粮食温度监测方法有望应用于储粮中的热点监测.

In order to find out the hot spots in stored grain more timely, a temperature monitoring method for stored grain based on acoustic tomography was proposed. The functional relationship between the sound travel-time in grain and grain temperature was derived. A sound velocity conversion factor was defined to convert the measured sound velocity in grain into that in the free space with the same temperature and gas, and an acoustic temperature measurement model for stored grain was established. The factors influencing the velocity conversion factor and the corresponding control measures were analyzed. The temperature-monitoring experimental system based on acoustic tomography of virtual instrument was developed. Through filling the experimental granary with soybean, the distribution rule of measured sound velocity for each sound path of the system was studied. In addition, the modification and convertion methods were proposed. Three kinds of grain temperature distribution generated by electric heaters were reconstructed in the testes. The results indicate that the reconstructed images can clearly reflect the location and temperature values of hot spots in soybean. Therefore, the temperature monitoring method for stored grain based on acoustic tomography is expected to be used for monitoring the hot spots in stored grain.