电阻抗扫描成像完备参数提取算法

为了提升电阻抗扫描成像的性能,本文提出了一个完备参数提取算法。该算法由前向问题建模以及参数提取两部分构成。前向问题模型基于静电散射理论,通过该模型可以获得前向问题的解析解。与常用的采用迭代过程的前向问题求解方法相比,采用新模型的前向问题求解速度大大提高。基于提出的前向问题模型,参数提取可以视作一个约束优化问题并采用改进的单纯形算法求解。仿真实验表明,完备参数提取算法与已有的参数或信息提取算法相比,不仅能够获得乳腺癌病灶更多的信息,并且准确度和鲁棒性更好。

电阻抗扫描成像病灶信息提取算法研究

为了提高电阻抗扫描成像在检查乳腺疾病中的性能,提出一种基于静电散射模型的乳腺病灶信息提取方法。基于一个放置于初始均匀电场中的电导率常数为σ1、半径为a的球体作为乳腺癌的模型,经过一系列的公式推导,给出一个提取乳腺癌病灶参数的方法。基于边界元方法对该模型进行了数值仿真。仿真结果表明,该模型可以有效地提取乳腺癌病灶的参数信息。

Piezoelectric responses of brittle rock mass containing quartz to static stress and exploding stress wave respectively

The electromagnetic emission(EME) induced from the rock containing piezoelectric materials was investigated under both static stress and exploding stress wave in the view of piezoelectric effect. The results show that the intensity of the EME induced from the rock under static stress increases with increasing stress level and loading rate; the relationship between the amplitude of the EME from the rock under different modes of stress wave and elastic parameters and propagation distance was presented. The intensity of the EME relates not only to the strength and elastic moduli of rock masses,but also to the initial damage of the rock. The intensity of EME induced by stress wave reaches the highest at the explosion-center and attenuates with the propagation distance. The intensity of EME increases with increasing the elastic modulus and decreases with increasing initial damage. The results are in good agreement with the experimental results.