中文摘要：

在电容层析成像（electricalcapacitancetomography，ECT）图像重建中，测量电容需根据高、低介电常数进行归一化处理。并联模型为常用的归一化模型，其归一化电容值与测量电容值为线性关系。串联归一化模型，其归一化电容值与测量电容值则为非线性关系，与并联归一化模型相比，重建图像有所改善。最新提出的基于电力中心线的混联模型为并联及串联归一化模型的混合，该文针对混联归一化模型提出了确定模型因子的多阈值方法。仿真及实验结果表明，基于多阈值的混联归一化模型，其重建图像质量得到较大提高。

英文摘要：

During the image reconstruction of electrical capacitance tomography （ECT）, the measured capacitances by ECT system are usually normalized at the high and low permitfivity for image. Parallel normalization model is commonly used during normalization process, which assumes the distribution of materials in parallel. And thus, the normalized capacitance is a linear function of measured capacitance. The usage of series normalization model results in the normalized capacitance as a nonlinear function of measured capacitance. The reconstructed images are improved using series normalization model compared with parallel normalization model. The newest presented combined model is based on electrical field centre lines （EFCL）, which is a mixture of two normalization models. The multi-threshold method for combined model was presented. Simulation and experimental results show that reconstructed images with higher quality can be obtained based on the combined model and presented multi-threshold method.