An Improved Genetic Algorithm In The Application Of Rural Tree-shaped Water Supply Network Optimization Design

The rural water supply system is the important basical facilitie, plays an irreplaceable role in developing rural economy and increasing farmers' income and ensuring the rural drinking water safety and improving farmers' life, is the inevitable requirement to construct the new rural and reduce the city and countryside disparity. Therefore completing perfectly rural water supply project has significant practical meaning.The infrastructure investment of water supply network is the highest of the entire water supply system, and the huge energy consumption of the system generally accounts for 60% to 80% of the total project investment. Because that economic foundation of the rural is weak and residents inhabitancy scattered and water supply area is bigger and water supply pipes are long and so on, rural water supply network also takes the form of a tree-shaped or mixed pipe network. This is different from urban circular water supply network calculation. The thesis author consults domestic and foreign relevant research reference literature and collects fully material to pursue the best plan of rural water supply network planning and the most reasonable calculation method.The specific solutions as follows:(1) Water supply network multiobjective model is established. This paper has referenced a large number of documents, analyzed pipe network reliability and used node surplus head to measure pipe network reliability, to set up pipe network optimization design multiobjective model. Namely, target function is that the sum of the node surplus head and the pipeline construction cost and operation management cost are the minimum, and the model constraints includes the standard and minimum pipeline diameter constraints, node water head constraint, hydraulic balance constraint, pipe flow velocity constraint, pump station output of supplying water and so on.(2) Network optimization arrangement is the premise of the pipeline network optimization design. Seeking the shortest total length of pipe is the goal, using the dynamic planning theory to find the best layout of tree-shaped pipeline network.The optimum arrangement of tree-shaped pipeline network is divided into two stages.The first stage is that according to designers experience forms several arrangement schemes complying with the design specification.The second stage bases on the first stage, using the dynamic planning theory to study the pipe diameter optimization problem of each arrangement scheme.(3) In view of rural water supply network reconstruction project and network project day by day increasing, the water supply style is developed gradually from single village water supply style to centralized supply style and some villages water supply style. This paper follow the shortest distance principle to probe how to accomplish reasonable connection and layout between different areas, to build relevant the mathematical model of optimum design.(4) According to the characteristics of pipe network calculation, this paper used integer coding, roulette wheel selection, arithmetic crossover method suiting for integer coding, improved mutation rate, and used penalty function to forme the constraint problem into the constraint problem.(5) There is a new rural water supply project example of CaoHe town YanZhou district Shandong province. This paper uses matlab to program calculation.The calculation results show that because of using the modified genetic algorithm the total cost has saved 92100 yuan.The paper is aimed at through the above research to offer a optimization method for new construction and reconstruction of rural water supply pipe network, and under the condition of pipe network hydraulic stability and reliability seek the cost minimization of year construction fee and operation management fee. So this paper study has certain theory value and practical value.