为了更好地逼近真实物理场景,对传统的多指数模型作了一些改进,将权因子设置为噪声方差平方的倒数,提出一种基于循环矩阵(CM)的算法用于估计衰减项数.为了求解上述改进模型,提出一种混沌免疫粒子群优化(CIPSO)算法.该算法将人工免疫系统中的克隆、交叉、变异和接收器修正算法嵌入粒子群算法中,并采用混沌算子实现变异,然后将惯性因子改为自适应变化.实验表明:提出的权因子设置更符合实际;用于估计项数的CM算法在估计精度与运行时间上均优于传统的ILS算法;CIPSO算法在收敛精度与运行时间上也优于传统的优化算法,如可信域法、LM法、高斯-牛顿法、差分进化算法和粒子群算法等.
In order to approach practical physical scene, traditional multi-exponential model is improved as follows: the weight factor is set as the reciprocal of the square of noise variance, and a method based on circular matrix (CM) is proposed to estimate the number of decay terms. To efficiently solve this model, a novel algorithm called chaotic immune particle swarm optimization (CIPSO) is proposed. The operators of clone, crossover, mutation, and receptor editing are embedded into particle swarm optimization; the chaotic operator is used to realize mutation, and the inertial factor is stipulated as adaptive variation. Experiments demonstrate that the proposed setting of weight factor is more practical; the CM method is superior to traditional iterative least square (ILS) method in terms of estimation accuracy and computation time; the CIPSO algorithm outperforms traditional optimization methods such as the trust-region method, Levenberg-Marquardt (LM) method, Gaussian-Newton method, difference evolution algorithm, PSO algorithm in terms of convergence accuracy and computation time.