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史义雄 《中国农村水利水电》2009,(9):28-31
基于图论原理对污水管网进行拓扑分析,利用矩阵存储管网信息数据,可以直观表达整个污水管网节点与管段的衔接关系,有效控制关键节点水力参数,实现对整个管网计算的优化。结合实例,采用Excel附带的编程语言VBA编写计算程序,验证了算法的可行性。该模型具有较强的纠错机制和通用性,可以应用到其他污水管网工程的设计中。 相似文献
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周积善 《中国农村水利水电》2003,(12):34-35
利用Excel强大功能,采取最简单有效的输入方法,执行乡镇供水工程树枝状管网一次性全过程水力计算。由于各种管材、管径水力要素和中间计算结果是动态平衡和可视的,因而除了计算省工省时和准确外,最主要是十分方便地对管网进行优化设计,节约工程投资。 相似文献
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介绍了基于管网基本定理的复杂管网分析法(节点法),提出了复杂管网分析计算的数学模型,利用该模型可以通过复杂管网的邻接矩阵将简单管道与复杂管网的分析方法统一起来.还探讨了该模型的求解问题,给出了非线性矩阵方程的迭代解法初始参数的计算方法.利用本文提出的模型方法可充分利用电子计算机进行管网实时动态模拟,可准确给出管网系统的实时状态,以及管网与水源联合工作的状态变化等. 相似文献
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自压喷灌干管管网的优化计算 总被引:3,自引:2,他引:3
结合自压喷灌的特点,以干管管网投资之和最小为目标函数,以标准(商用)管径,管长为优化变量,建立了自压喷灌干管网优化计算的线性规划模型,在管网布置方案确定后,利用这一方法,可进行了干管管网的优化设计。 相似文献
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利用正交表优化设计自压式低压管灌系统 总被引:7,自引:0,他引:7
在渠灌区,研究充分利用地形落差情况下自压式低压管灌树状管网的优化设计,对降低投资有重要意义。管网优化设计应将管网布置优化和管径优化结合进行设计。本文利用正交表及其优化分析原理,同时结合应用非线性数学规划法优化管径,不仅可得到所有管网布置组合中的最优方案,还可视实际需要得到若干次优方案。该优化设计法计算工作量较小,简单可靠且实用。 相似文献
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在渠灌区,研究充分利用地形落差情况下自压式低压管灌树状管网的优化设计,对降低投资有重要意义,管网优化设计应将管网布置优化和管径优化结合进行设计,本文利用正交表及其优化分析原理,同时结合应用非线性数学规划法优化管径,不仅可得到所有管网布置组合中的量佳方案,还可视实际需要得到若干次优方案。该优化设计法计算工作量较小,简单可靠且实用。 相似文献
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本文全面考虑了环状供水管网的工作特点及工作要求,建立以管网总投资最小为目标函数,管网节点要求的供水量及供水压力为约束条件的管网管径优化计算的非线性规划数学模型。同时在约束条件中考虑了多水源供水时的水资源最优化分配问题。并根据近似规划法的优化原理将非线性规划问题转化成线性规划问题,采用单纯形法进行求解。本方法适合于环状网、树环结合管网及多水源管网的管径优化计算。 相似文献
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规模化管道输水灌溉管网优化模型研究与应用 总被引:1,自引:0,他引:1
《节水灌溉》2015,(10)
结合山东省小型农田水利重点县建设,在总结现有管网优化设计研究成果的基础上,分析了沿程水头损失计算方法,探讨管网费用函数,建立了规模化管灌工程管网优化模型,利用界限流量法进行优化求解,该方法简便,可操作性强,对降低工程投资,减少运行费用具有重要意义。 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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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
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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