Study On Nonlinear Modeling For Particle Size Measurement Based On Ultrasound In Mineral Slurry

Ultrasonic technique as a particle sizing analysis is given more and more attentions for its advantages, for example, extremely wide size rang of particles and especially in high concentration condition, as well as its adaptability to the on-line measurement , and developed quickly. But because of trade secret and absence of technique, research results are seldom reported. Therefore, it is terribly necessary and urgent to start our research work in this area to fill up the blankness of our country. The society significance as well as its economy importance sticks out a mile.Based on anglicizing the existing theoretical model of ultrasonic particle size measurement, the function of the cumulative undersize against the particle size, which is in the case of particle size distribution, is inserted the existing theoretical model, thereby, the theoretical model of ultrasonic particle size measurement based on fractal modification on the case of composite particle size distribution is derived. Effects of irregularity, rough surface and aggregation of particles on ultrasonic attenuation are significant. The effects should be considered while predicting particle size by ultrasonic attenuation technology.ωτv is used as the scale in long wave-length regime, andκR is used as the scale in scattering regime, the nonlinear model of ultrasonic particle size measurement based on fractal modification is proposed. The result of experimental data and analogue calculation indicated that predictions of the nonlinear model of ultrasonic particle size measurement based on fractal modification show good agreement with experimental data, which show this nonlinear model effective.The method of inversely calculation to particle size distribution parameters and deviated index between fractal dimensions in the nonlinear model are developed. Utilizing periodicity of chaos optimization and inversion of genetic algorithm, an improved chaos genetic algorithm for calculating particle size distribution parameters and deviated index between fractal dimensions is developed and the realizing steps of the algorithm are given.The goal function for inversely calculating particle size distribution parameters and deviated index between fractal dimensions has information of particle size distribution parameters and deviated index between fractal dimensions, and both are interactive. To avoid their interactive, the inversely strategy is developed, its principle is the particle size distribution parameters and deviated index between fractal dimensions are inversely calculated respectively and by turn, step by step optimized to close to the best values. The results of numerical simulations and experimental research show this algorithm has the advantages of high precise and high stability. The weight percentage of particles of mineral slurry is an unknown quantity in the the nonlinear model of ultrasonic particle size measurement based on fractal modification. In this study, the method ,which is on the case of the knowing weight percentage of particles of mineral slurry, and the double wavelength method are used to inversely calculate the optimized particle size distribution parameters and deviated index between fractal dimensions, especially, the double wavelength method has important application significance for online measuring particle size distribution of mineral slurry.Different type mineral is used to test the nonlinear model of ultrasonic particle size measurement based on fractal modification, the testing result show the inversely calculating values of model are good agreement with experimental data, which show this nonlinear model effective and utilizable.