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毫州市节水灌溉工程运行机制问题及对策 总被引:2,自引:0,他引:2
以安徽省毫州市为例,针对节水灌溉工程普遍存在的运行问题进行了探讨。通过分析,指出节水灌溉工程利用率低、效益发挥不理想的根本症结在于没有建立一个科学的运行机制,并根据毫州市的实践提出相应的对策。 相似文献
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基于框架网络建立了节水灌溉工程选型专家系统 ,引入的继承和重载、隐含匹配、默认匹配等概念 ,使知识表示和推理过程更加适合节水灌溉工程选型的特点。系统提供的标准知识库涵盖了常用的各种节水灌溉工程形式 ,提高了专家系统的实用性。 相似文献
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微灌用砂过滤器的过滤与反冲洗 总被引:2,自引:0,他引:2
董文楚 《中国农村水利水电》1996,(12):15-19
对节水灌溉工程中使用的砂过滤器的过滤与反冲洗性能进行理论分析和试验研究,提出了新的过滤阻力系数与雷诺数的关系式,给出了新的计算初始水头损失公式。分析了过滤和堵塞的规律,并根据反冲洗试验结果,提出了最佳反冲洗强度和最佳膨胀率,为正确设计和使用砂过滤器提供了理论依据。 相似文献
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建立灌区用水者协会的水权制度,对明晰用水者协会的产权制度的有着重要的作用。在对水权、区域水权、初试水权论述的基础上,对灌区用水者协会的水权进行了探讨。用水者协会的水权是农业水权中的灌溉水权,是由其所辖灌溉工程决定的、灌区管理单位(或供水公司)移交(或转移)的灌溉水的权利,包括占有权、支配权、使用权和收益权。用水者协会的水权的特征主要表现为水的所有权为国家所有,其占有权、支配权、使用权和收益权为用水者协会集体所有,协会水权经灌溉工程产权移交后产生,并具有初试水权的特性。灌区用水者协会的水权量一般用水量、水权面积表示。 相似文献
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第二章 对现有灌溉系统的诊断2 .1现有设施运转状况对原有灌溉工程的运行及其目标产生影响的因素要进行重新审查 ,以便了解工程系统现状及其运行情况 ,为将来改造目标的实现提供有用的资料。对灌溉工程考虑进行修复和现代化改造 ,普遍的理由是灌排系统的实体部分老化 ,使其限制了农业生产的发展。由此带来的损失对所有用水户的反应是不平均的。因此 ,在全灌区内恢复公平和对用水者提供可靠的服务要特别加以考虑 ,对灌溉工程现状及现有设施适应性的评估是确定灌溉工程如何提高的主要工作内容。因此 ,在打算进行现有设施的改善或改建时 ,安排… 相似文献
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灌溉渠系水利用系数的分析与计算 总被引:6,自引:0,他引:6
灌溉渠系的布置形式一般可分为串联渠系,等效并联渠系和非等效关联渠系,对这3种灌溉渠系水利用系数进行了理论研究,用实例验证了上述的理论分析,研究成果可应用于实际灌溉工程。 相似文献
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《Journal of Agricultural Engineering Research》1998,69(3):249-254
A model to represent the discolouration of dried powder of carrots as a function of temperature was developed. Two types of carrots, Asian and European, containing large amount of lycopene and β-carotene, respectively, were tested. The dried powder was stored under an atmosphere with O2and at three different temperatures, 5,20 and 35°C. The surface colour of the powder was monitored during storage by a Hunter colour ratioa/b. In the proposed model, the rate of oxidation was assumed to be represented by the product of the fraction of concentration of oxidized pigment at arbitrary time and a specific rate of oxidation of pigment. The rate parameters in the proposed model were calculated by fitting the experimental data with smooth curves by trial and error at the end of the induction period but before discolouration took place. The frequency constant and activation energy, expressing the temperature dependence of the rate parameters, were expressed by the Arrhenius relation. The simulation results of a Hunter colour ratioa/bof dried powder at 25°C showed good agreement with the experimental data, suggesting that the proposed model was effective for the prediction of discolouration of dried powder of both types of carrot. The use of the induction period in the manner described may enable the shelf life of dried powder to be predicted. 相似文献
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感官检验棉花的品级,这是农村常见的一种检测手段.它的一个主要特点就是存在不确定性.这是由于检验员的品级检验水平存在一定的差异,其中有很多因素制约着检验的结果.文章对影响感官检验结果的因素进行了系统的分析. 相似文献
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从灾害经济学的角度探讨了城镇供水优化调度的必要性和可能性,认为在缺水不可避免的情况下,对供水进行优化调度可以减小缺水带来的损失,产生较好的减灾效益,特别是可以大大减小严重干旱的灾害效应。并根据水资源的特性,提出了缺水损失的计算模式以及优化调度的原则和方法。 相似文献
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The fractional outflow rate of water from the rumen, measured as the rate of disappearance of the chromium complex of ethylenediamine tetra-acetic acid, was related to a number of dietary factors. A multiple regression equation was derived which expressed fractional outflow rate as a function of the intakes of dry matter, ash, acid-detergent fibre and crude protein.The data analysed consisted of 243 observations for sheep on 59 diets, including forage, concentrate and mixed diets. The ranges covered by the data were: fractional outflow rate 0.7–3.6 day?1; dry matter intake 560–1400g/day; ash 4–30%, acid-detergent fibre 7–41%, crude protein 5–26 % of dry matter; there were no observations for sheep of less than 34 kg liveweight.The equation accounted for 56·3 % of the total variance. Between-sheep variance could not be calculated for the whole of the data but was undoubtedly substantial since, for a sixth of the data, it was known to account for 38 % of the total variance. 相似文献