Research And Development Of Optimization Method And Aided Design Software For Gravity-driven Drip Irrigation Pipe Network System

Gravity-driven drip irrigation pipe network(GDIPN)system takes advantage of the terrain drop to form water heads to meet the water head requirement of each water demand node in the pipe network.It has the advantages of economical and energy saving.The optimization design of GDIPN system is a multi-objective,multi-constraint,and complex optimization problem.In the past,most researches focused on the optimization of pipeline layout and pipe diameters of field pipe network system(FPNS).The methods they used were mostly insufficient in generality.And few scholars have studied the optimization of the main pipe system(MPS)with pressure regulating facilities.In this study,according to the shortcomings of the current researches on the optimization design of GDIPN system,the component of GDIPN system and the design points and difficulties of each component were analyzed and summarized.A robust and efficient algorithm,named genetic algorithm,was taken as the core optimization algorithm of pipe network design.By scientific coding and decoding,the optimization algorithm can be in common use.The optimization algorithms codes were packaged into two online applications.And a simple website was preliminarily developed and used to test and apply the optimization design applications.The main research contents and conclusions are as follows:(1)The design points of the FPNS of GDIPN system were analyzed.The optimization mathematical model of the FPNS was constructed.Taking a genetic algorithm based on infeasibility degree as the core,an optimization algorithm was developed.An engineering example was used to verify and evaluate the optimization algorithm.The results showed that under the condition of meeting the design requirements,the optimized design was more reasonable than the original design in the form of pipe network layout.The variable diameter design method was used in the pipe diameter optimization of the same level pipeline in the optimized design,which was more economical than the single diameter design method of the original design.The total cost of pipe network of the optimized design was greatly reduced,which was 36.7% less than the original design.(2)The optimization design problem of the MPS of GDIPN system was analyzed and generalized.The optimization mathematical model of the MPS was constructed.A multiobjective optimization algorithm based on nondominated sorting genetic algorithm-?(NSGA-?)was developed and was verified and evaluated by an engineering example.Finally,several Pareto optimal designs(optimized designs)were obtained by the optimization algorithm,which achieved the dynamic balance of economic and security objectives.Comparing the three typical optimized designs with the original one,the results showed that the three optimized designs were more economical in the selection of pipe diameter of multiple pipe sections.The total cost of the optimized designs could be saved up to 27.6% compared with the original design,indicating that the optimization algorithm could achieve good economic benefits.In terms of safety objectives,the maximum standard deviation of water heads at the entrance of submain pipes of the optimized designs was 4.61 m,which was obviously smaller than the original design's 8.00 m.Moreover,the optimized designs only needed to install 4 pressure reducing valves at most,which were less than 9 of the original design.It could be seen that the water heads of the optimized designs were more balanced,which was more conducive to the safe operation of the MPS.(3)The optimization algorithms for GDIPN system design based on MATLAB programming were packaged into two simple online aided network optimization design applications.A simple website was preliminarily developed.The integration of these two optimization applications and the website was basically realized.The website was tested by using an optimization design problem of a MPS of GDIPN system,and the results showed that the website was easy to use and had complete functions,which could help users to quickly and efficiently achieve the online optimization design of GDIPN system.The optimization design of GDIPN system is actually a very complicated problem.In this paper,some appropriate simplification and assumptions were made in the process of the research of GDIPN system.Therefore,the optimal design of GDIPN obtained by using the developed optimization algorithm is an ideal design.Before an optimized design is put into service,users should adjust the design based on the optimized design according to the actual situation.In addition,the developed applications and website are relatively simple and need to be improved in the future.