双峰分布的超细颗粒动态光散射信号模拟及精度分析

为获取双峰分布超细颗粒的动态光散射模拟信号,通过建立动态光散射随机过程的AR模型,利用修正的Levison Durbin递推算法确定模型参数和阶数的方法模拟光散射信号.分别对10 nm与90 nm,200 nm与1 000 nm双峰分布颗粒的动态光散射信号进行模拟,得到的模拟信号光强自相关函数与理论值吻合,用双指数法对颗粒粒径反演,相对误差小于3.55%.通过分析模型阶数、采样时间、采样频率、模拟数据长度等参数对模拟精度的影响,得出双峰分布颗粒光散射信号的模拟精度与各参数的关系:在低于阈值阶数时,模型阶数选择对精度影响大,模型阶数越高,信号模拟的精度越高,高于阈值阶数时,模型阶数选择对精度影响不大,可选阈值阶数模型模拟信号.选定一定的采样时间,采样频率越高,模拟数据长度越长,模拟精度越高.

Computer Simulation of Bimodal Distribution Ultrafine Particles Dynamic LightScattering and Precision Analysis

In order to simulate the dynamic light scattering signal of the bimodal distribution ultrafine particles,through setting up auto regressive (AR) module of dynamic light scattering random process.The simulation signal of the dynamic light scattering can be acquired by this method. The light scattering signals of 10 nm and 90 nm, 200nm and 1000 nm with bimodal distribution particles are respectively simulated by the computer. The autocorrelation function of the simulated light intensity is nearly identical to its theory autocorrelation function. The relative error of inverting particle size by double exponential is less than 3.55%. Analyzing influence of parameters such as the module order ,sample time, sample frequency, simulation data length on simulation precision, the relation of simulation precision and parameters can be drawn.When the order is lower than the threshold order, the simulation precision is highly affected by the module order.The simulation precision will increase with the increase of the module.When the order is higher than the threshold order, the simulation precision is lowly affected by the module order. Therefore, the threshold order can be used in simulation.Selecting the certain sample time,the simulation date length and simulation percision will increase with the increase of the sample freguency.