【作者】 皮丽辉；

【导师】 温新明；

【作者基本信息】 石河子大学 ， 农业水土工程， 2008， 硕士

【摘要】 我国是一个缺水的国家,水资源短缺严重影响国民经济和社会的可持续发展,现代节水灌溉技术能够在一定程度上缓解农业用水资源短缺的矛盾,但是节水灌溉管网系统工程投资较大,不利于这类技术的推广和提高。地下滴灌作为一种高效的节水灌溉方式之一,分析管网水力计算有助于研究地下滴灌管网的水力特性,管网优化设计可以有效降低系统的整体投资,对进一步推动地下滴灌发展具有重要意义。本文在综述国内外地下滴灌技术发展动态和管网水力计算及优化设计的研究现状基础上,着重研究了以下三方面内容。(1)分析地下滴灌环状管网水力计算及优化规划模型建立的评价标准和系统条件。通过分析环状管网的水力特性,研究地下滴灌环状管网沿程水头差和节点流量计算,为提出管网优化模型的系统条件奠定基础。在借鉴前人所建管网优化设计模型的基础上,以年费用最低为目标,以离散管径的造价公式为基础,建立了地下滴灌系统在轮灌条件下的确定性非线性规划模型,并推导出不考虑约束时管径优化的技术经济法和界限流量法。(2)建立了地下滴灌随机供水的优化设计模型。在地下滴灌系统的优化设计中,不同的灌溉工作制度在管网各设计管段中产生不同的流量分配模式,这直接影响到管网工程总投资的大小。地下滴灌系统往往采用轮灌的运行方式,这种方式并不考虑地块内作物对需水的要求差异。针对这种灌溉工作制度的缺点,本文以净效益最大为目标,建立了地下滴灌系统随机灌水条件下的管网优化模型,为管网优化设计和投资评价中选择合理的灌溉工作制度提供一定的技术依据。(3)研究了非线性地下滴灌系统优化设计的遗传算法。近年来,遗传算法被广泛应用于城市给水管网的设计中,但在地下滴灌中的应用很少。本文在分析遗传算法的原理及应用遗传算法求解地下滴灌管网优化模型的实现步骤基础上,采用遗传算法对以上所建具有离散特点的多元、非线性地下滴灌系统优化模型进行求解,并结合实例进行了分析计算,效果令人满意,说明其方法基本可行,并具有一定的实用性。更多还原

【Abstract】 Becourse China was a water-scarcity country, that has influenced seriously our national economy and society’s sustainable development.The modern water-saving irrigation techniques alleviated the shortage of water resources contradictions, but the water-saving irrigation economic investment higher, disadvantage in this technical expansion and exaltation. Subsurface drip irrigation is an efficient way of the water-saving irrigation Hydraulic calculation of pipe network redounds to investigating the hydraulic characteristic of the subsurface drip irrigation network. Design optimization of the SDI system can effectively reduce the overall investment of the system. It is of great significance to promote further the development of subsurface drip irrigation.On the base of analyzed the technology developments of the subsurface drip irrigation and reviewed hydraulic calculation of pipe network and the optimization theory of optimum planning of SDI, the main content of this paper is as following:Firstly, analyze the hydraulic calculation of SDI networks and the evaluation criteria and the system condition to establish optimization model. Through the analysis the hydraulic characteristic of the circular network pipe, to study along the regulation flood peak difference and the node current capacity computation of the subsurface drip irrigation circle network, to lay the foundation for proposing the system conditions that restraint the pipe network optimizal model.On the base of using for reference of models which is founded by the elders, through taking annual minimum cost as the objective function, taking the cost formula of pipe network as the foundation, taking diameter as optimization variable, the nonlinear programming models by working in turn is founded. According to the model, the solution of technology & economy and flow bounds approach is detruded.Secondly, stochastic non-linear programming by random irrigating are presented to optimize the diameters of network. In SDI, the mode of working in turn did not concern the different of crop, so the paper take net benefit as the objective function, a new model for optimal design of SDI network by random irrigating is developed, this can be used in choosing reasonable irrigation schedule and saving much more investment.Thirdly, the author introduced the theory of genetic algorithm and solved the two models which have the characters of many discrete and mixed variables and nonlinear by genetic algorithm. Furthermore, the author took the calculation and analysis by combing each model with living example and get satisfactory result. All these proved that these models and solution had both notable economic benefits and highly practical value.更多还原