Analysis Of Acoustic Propagation Characteristics Of Ultrasonically Irradiated Plant Seeds

With the upgrading of science and technology and the rapid development of agriculture,as well as the promotion of various actual needs,various professional technical systems show a strong trend of integration,penetration and integration,and then put forward the concept of biological agriculture.More than 40 years since the reform and opening up,people pursuit of agriculture from merely increase grain production,gradually evolved into the promotion product health level,therefore our biological agriculture concept from the beginning of farming and farming industry,gradually develop to guided by new biological breeding new agricultural modernization,from then on,people began to look at a variety of different disciplines in the field of theory,means,methods,tools,and The equipment is used in agricultural breeding.Ultrasonic breeding is a new idea of biological breeding,which is a purely physical method--ultrasonic to stimulate plant seeds.Because of the interaction between ultrasonic wave and plant seeds,it will cause a series of beneficial physical changes,so it is often used to radiate plant seeds,so as to achieve the effect of awakening plant seeds,accelerating plant growth rate,promoting seed breaking and shortening the growth period.Most of the existing ultrasonic breeding technologies are only in the experimental stage,and lack of theoretical basis,and can only rely on experience to select some radiation parameters,which are subjective,blind and random.The purpose of this paper is to conform to the actual situation of plant seeds structure model is established to simulate the interaction between ultrasonic and plant seeds,considering plant seeds of ultrasonic attenuation,realize the passband frequency band range,sensitive to radiation frequency and incident Angle,the choice of offering theoretical reference for breeding of ultrasonic,at the same time,promote the development of agricultural breeding level.The main research contents of this paper are as follows:1.The continuous and uniform layered medium model of plant seeds was constructed.Due to the differences in the structure of nutrients and materials in different parts of plant seeds,the acoustic characteristics of the seeds are also different.Based on the layered characteristics of plant seeds,a continuous and uniform layered medium model was established to simulate the interaction between ultrasonic waves and plant seeds.By clarifying the reason of the decreasing amplitude of acoustic wave propagation in non-ideal medium,it is found that the attenuation of acoustic wave in medium is restricted by its diffusion,scattering and absorption.In ultrasonic breeding needs first to seed soaking water absorption,and seed contains a large amount of nutrients,so the seeds can be as a kind of fluid substance,its acoustic attenuation is mainly derived from the inner friction power caused by the viscous absorption,so small amplitude of acoustic wave equation in the ideal fluid,on the basis of the research process to consider medium viscosity.2.The acoustic wave equation in viscous fluid is applied to the analysis of the acoustic propagation characteristics of plant seeds,and the reflection coefficient and transmission coefficient are selected to study the acoustic propagation characteristics of plant seeds.Because the interface of the layered medium model of plant seeds will reflect and refraction the ultrasonic wave;At the same time,each layer of medium in plant seeds will produce phase change and sound attenuation effect on ultrasonic wave,so the reflected wave and transmitted wave carry a lot of information about the acoustic characteristics of the medium.The reflection coefficient and transmission coefficient which can represent the acoustic parameters of plant seeds are also selected to study the acoustic propagation characteristics.The effects of acoustic impedance rate,multiple reflection,ultrasonic frequency,incident Angle and sound attenuation on the acoustic propagation characteristics were considered in the research process,which provided a basis for further selection of suitable breeding parameters for specific seeds.3.Choose life common bean class mung bean seeds and peanuts,seeds,based on the seed structure,build the leguminous seeds ellipsoid layered medium model,from the selection of ultrasonic wave incident direction section construction of seed embryoseed three layer medium model,based on the phonon crystal model,then calculate the mung bean seeds and peanut seeds pass band frequency range;Secondly,the influence of incident Angle and radiation frequency on the transmission coefficient is analyzed through MATLAB numerical simulation of the change curve of sound pressure transmission coefficient,and then the resonance fundamental frequency and the appropriate incident Angle are found without considering the sound attenuation.Finally,based on COMSOL,the finite element simulation of the sound field of the seeds of plants exposed to ultrasonic radiation was carried out to select the sensitive frequency when considering the sound attenuation,which provides theoretical reference for the parameter selection of subsequent ultrasonic breeding and reduces the subjectivity,repeatability and randomness of the experiment.