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Leakage Detection in Water Distribution Network Based on a New Heuristic Genetic Algorithm Model 被引量:4
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作者 Ali Nasirian Mahmoud F. Maghrebi Siavash Yazdani 《Journal of Water Resource and Protection》 2013年第3期294-303,共10页
The leakage control is an important task, because it is associated with some problems such as economic loss, safety concerns, and environmental damages. The pervious methods which have already been devised for leakage... The leakage control is an important task, because it is associated with some problems such as economic loss, safety concerns, and environmental damages. The pervious methods which have already been devised for leakage detection are not only expensive and time consuming, but also have a low efficient. As a result, the global leakage detection methods such as leak detection based on simulation and calibration of the network have been considered recently. In this research, leak detection based on calibration in two hypothetical and a laboratorial networks is considered. Additionally a novel optimization method called step-by-step elimination method (SSEM) combining with a genetic algorithm (GA) is introduced to calibration and leakage detection in networks. This method step-by-step detects and eliminates the nodes that provide no contribution in leakage among uncertain parameters of calibration of a network. The proposed method initiates with an ordinary calibration for a studied network, follow by elimination of suspicious nodes among adjusted parameters, then, the network is re-calibrated. Finally the process is repeated until the numbers of unknown demands are equal to the desired numbers or the exact leakage locations and values are determined. These investigations illustrate the capability of this method for detecting the locations and sizes of leakages. 展开更多
关键词 CALIBRATION ssem WATER DISTRIBUTION LEAK Detection GENETIC ALGORITHM
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电子组装中PCBA清洗技术 被引量:2
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作者 宋顺美 史建卫 《电子工业专用设备》 2014年第4期27-37,共11页
清洗对于电子产品可靠性有着非常重要的影响,针对印制电路组件污染物进行了系统阐述,并对不同的清洗技术和工艺进行了总结归纳,讨论了影响清洗效果的各个因素及其检验规范,为实际生产起到了指导性作用。
关键词 印制电路组件 污染物 助焊剂残留 清洗技术 离子浓度 半水清洗工艺
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农村劳动力转移、化肥施用强度与农业生态效率:交互影响与空间溢出 被引量:50
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作者 侯孟阳 邓元杰 姚顺波 《农业技术经济》 CSSCI 北大核心 2021年第10期79-94,共16页
基于1987—2017年省级面板数据,并考虑到地区间的农业生产空间交流与依赖,本文构建空间联立方程模型,采用广义空间三阶段最小二乘(GS3SLS)法探讨农村劳动力转移、化肥施用强度与农业生态效率间的双向交互影响和空间溢出,并进一步讨论了... 基于1987—2017年省级面板数据,并考虑到地区间的农业生产空间交流与依赖,本文构建空间联立方程模型,采用广义空间三阶段最小二乘(GS3SLS)法探讨农村劳动力转移、化肥施用强度与农业生态效率间的双向交互影响和空间溢出,并进一步讨论了不同区域空间交互影响的差异性。研究发现,空间联立方程的运用不仅有效解决了变量间内生性问题,也能考虑到内生变量的潜在空间相关性。化肥施用强度与农业生态效率之间存在显著的交互效应及空间溢出效应,化肥施用强度的增加会导致农业生态效率的下降,由于时间滞后效应的存在,农业生态效率的提升反而在一定程度上会提高化肥施用强度;农业生态效率与农村劳动力转移、农业机械投入分别存在显著的负向、正向交互影响,而化肥施用强度与农村劳动力转移、农业机械投入分别存在显著的正向、负向交互影响,农村劳动力转移与农业机械投入则表现出显著的正向交互影响;此外,空间交互影响的程度和方向在不同区域存在显著的差异性。 展开更多
关键词 农业生态效率 化肥面源污染 农村劳动力转移 空间交互影响 空间联立方程
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