Carbon Dioxide Intelligent Regulate Strategy For Greenhouse Based On Crop's Physiological Demand

Carbon dioxide is the necessary material in the dark reaction process of crop photosynthesis.Carbon dioxide has negative correlation trend between facility environment and actual needs of crops.Traditionally,facility environment is restricted to the threshold regulation mode with single factor,thus it cannot achieve the optimal supplement based on crop actual requirement as the consequence of crop photosynthetic rate is relatively low;Meanwhile,researches on homogeneity regulation of carbon dioxide have done less,which lead to the distribution of concentration in facilities space for carbon dioxide is uneven.In tackling these problems,this paper puts forward intelligent control method of crop carbon dioxide facilities based on crop's need,which merges the particle swarm optimization(PSO)algorithm by means of wavelet neural network(WNN),in order to establish the regulate model of carbon dioxide with facilities crops.We design intelligent monitoring equipment based on Wireless Sensor Network(WSN).According to relevant principles of fluid mechanics,we design different sizes of the hole in the gas pipeline for the homogeneity regulation.The system realizes dynamic,precise and homogeneity regulation based on crop actual requirement.The successful development of carbon dioxide all-round intelligent regulation system plays an important and supplementary role in improving facilities small environment.The thesis focuses on the following topics:(1)Building photosynthetic rate model of crops and carbon dioxide optimal regulation model in facilities.With the help of establishing response experiments on facilities tomato carbon dioxide,we decide to obtain the photosynthetic rate of test data,such as different temperature,light,carbon dioxide gradient.By means of WNN algorithm,we build the prediction model of photosynthetic rate,which the relevant precision of forecasting model is as high as 0.99,and the relevant absolute output error is as low as 0.8.According to the photosynthetic model,it uses the PSO algorithm to optimize photosynthetic rate under different conditions of temperature and illumination,in order to obtain carbon dioxide saturation point and build carbon dioxide regulation model.Compared with model and theoretical value,it is suggested that the correlation coefficient is as high as 0.954 and the relevant output error is as low as 4%.It proves that the regulate model has higher precision.(2)Building carbon dioxide regulation system based on WSN in facilities.According to the different nodes function in the network logic,regulation system is divided into three modules,including mastering,monitoring and fertilizing nodes.The development of system hardware involves in power module,sensor module and external communication module circuit principle diagram and design of PCB,so as to complete the collection of information,acquisition and setup of interactive hardware platform;The design of software mainly includes the industrial computer programming based on Linux and construct wireless sensor network based on ZigBee.Industrial computer mainly achieves model processing,human-computer interaction and the remote collaboration.It builds wireless sensor network based on the Z-Stack secondary development,which obtains environmental parameters to achieve monitoring,processing and control.Combined software with hardware design,it introduces systematic working process.(3)Function and performance verification of carbon dioxide regulation accuracy,uniformity and effectiveness.According to the theory of fluid mechanics,it determined the return of the relationship between relative depth of the fertilizing pipe and the hole size of pipeline,depending on the pressure,relative depth conditions and the theory of gas jet,so as to ensure the instantaneous flow equality.The experiment verified homogeneity,which the variation coefficient is as low as 3%.Under the condition of homogeneity regulation,the experiment verified precision,it is as low as 3.5%,which meets carbon dioxide regulation.With the control experiments,it is verified that carbon dioxide regulation system has effect on the actual photosynthetic rate of crops.The experiment resulted photosynthetic rate of crops was improved relatively in carbon dioxide regulation area.It meets the demand for carbon dioxide regulation in the facility environment.