Sensitivity analysis of optimal operation of irrigation supply systems with water quality considerations

A model for optimal operation of water supply/irrigation systems of various water quality sources, with treatment plants, multiple water quality conservative factors, and dilution junctions is presented. The objective function includes water cost at the sources, water conveyance costs which account for the hydraulics of the network indirectly, water treatment cost, and yield reduction costs of irrigated crops due to irrigation with poor quality water. The model can be used for systems with supply by canals as well as pipes, which serve both drinking water demands of urban/rural consumers and field irrigation requirements. The general nonlinear optimization problem has been simplified by decomposing it to a problem with linear constraints and nonlinear objective function. This problem is solved using the projected gradient method. The method is demonstrated for a regional water supply system in southern Israel that contains 39 pipes, 37 nodes, 11 sources, 10 agricultural consumers, and 4 domestic consumers. The optimal operation solution is described by discharge and salinity values for all pipes of the network. Sensitivity of the optimal solution to changes in the parameters is examined. The solution was found to be sensitive to the upper limit on drinking water quality, with total cost being reduced by 5% as the upper limit increases from 260 to 600 mg Cl l^–1. The effect of income from unit crop yield is more pronounced. An increase of income by a factor of 20 results in an increase of the total cost by a factor of 3, thus encouraging more use of fresh water as long as the marginal cost of water supply is smaller than the marginal decrease in yield loss. The effect of conveyance cost becomes more pronounced as its cost increases. An increase by a factor of 100 results in an increase of the total cost by about 14%. The network studied has a long pipe that connects two distinct parts of the network and permits the supply of fresh water from one part to the other. Increasing the maximum permitted discharge in this pipe from 0 to 200 m³ h^–1 reduces the total cost by 11%. Increasing the maximum discharge at one of the sources from 90 to 300 m³ h^–1 reduces the total cost by about 8%.     

35CrMo旋转接头激光表面硬化技术的试验研究

用L9(34)正交试验法研究35CrMo旋转接头激光相变硬化工艺参数优化组合,分析了旋转接头激光相变硬化方法.试验结果表明:激光相变硬化层硬度比渗氮淬火提高了30%,耐磨性提高了1倍,表面残余应力为压应力;满足了旋转接头工作要求,为改进旋转接头表面处理方法提供了依据.     

水分亏缺对覆膜玉米生长发育及产量的影响

通过系统的覆膜玉米亏水灌溉试验 ,研究了不同生育期内不同程度的水分亏缺对覆膜玉米生长发育、光合作用、产量及水分利用效率等的影响。结果表明 ,拔节期受旱对玉米株高及叶面积指数影响最大 ,抽雄后的水分亏缺对玉米生长发育影响不明显。各处理产量资料表明 ,覆膜春玉米的需水临界期为抽雄开花期 ,此期轻度的水分亏缺可造成产量大幅度下降 :灌浆期较抽雄开花期玉米产量对水分亏缺敏感程度低 ,但在这个阶段的水分亏缺也可使玉米减产 ;拔节期玉米产量对水分胁迫敏感程度较差 ,该阶段为对玉米进行水分亏缺处理的适宜时期     

玉米不同生育期水分胁迫指标

采用田间小区实验 ,通过对玉米不同生育期、不同土壤水分条件下叶水势、气孔导度、光合作用、植株蒸腾、生理生态状况及产量形成的观测试验 ,并在总结已有成果的基础上 ,分析研究了玉米不同生育阶段的水分胁迫指标阈值 ,提出了玉米不同生育阶段的水分胁迫指标 ,为节水灌溉与灌溉管理提供了科学、实用的依据。     

基于多周期同步测量的涡轮式流量测试研究

涡轮流量计是泵试验中常用的流量测试仪表之一。文章在讨论涡轮流量计的结构和基本原理的基础上,分析了“测频法”和“测周法”流量测试方法存在的精度不等的问题,提出了多周期同步测量技术在涡轮式流量测试中的应用,从而进一步提高了流量测试精度。     

我国北方地区节水农业技术水平及评价

在系统分析我国节水农业技术水平现状的基础上 ,对各类节水技术的差距和存在问题进行了探讨 ,提出了各类技术亟待研究解决的若干重点问题。并指出建立以渠道防渗技术、管道输水技术及地面灌水技术为核心 ,符合国情的节水农业技术体系已迫在眉睫。     

罗湾水电站引水系统过渡过程研究

为了对罗湾水电站增容前后的引水系统过渡过程和机组增容改造对引水系统建筑物的影响进行研究，应用水击计算方法中的电算法进行计算，得出了调压室最低、最高涌浪水位，蜗壳处最大压力水头和机组转速最大升高。结果表明，电站增容后引水系统完全能满足有关规范和设计的要求。     

泵站系统故障诊断智能PETRI网

以往应用系统故障诊断模型行为PETRI网中规则的可信度为固定常数，由于泵站工作状况在改变，因此，应用在泵站系统时，提出了以谓词变迁网（Pr／T－PN）存储知识，智能推理计算重要规则可信度的方法，并给出了明确的定义。以轴流泵出现动力机过载情况为例，说明了泵站系统故障诊断智能PETRI网的构造和诊断方法。     

Irrigation and food security in the 21st century

Global food projections indicate that food prices in the next threedecades will likely be stable or decline, but progress inreducing malnutrition in developing countries will be slow. Smallshortfalls in crop productivity growth would lead to rising foodprices and worsening malnutrition. Increased food production fromirrigation is essential, and will require expansion of irrigatedarea and water supplies, and improved efficiency of use of existingwater supplies. Neither of these growth factors will prove easy, andboth will require complex institutional and policy reforms. Failureto meet food production needs through efficient expansion andintensification of irrigated agriculture would increase pressure onland resources and hasten the process of environmental degradation.Irrigation and water development strategies have been hampered bya lack of understanding of the links between water scarcity, foodproduction, food security, and environmental sustainability.Research to improve this understanding would have high payoffs.     

春小麦高产叶龄模式的研究

本研究根据春小麦的叶龄进程，对水、肥、密等影响产量的主要因素进行优化组合，提出了旨在提高春小麦的产量及获得最佳效益的高产模式，为指导我国北方春小麦的生产提供了科学依据。