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不同深度基質(zhì)含水率變化規(guī)律與預(yù)測模型研究
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國家重點研發(fā)計劃項目(2019YFD1001903、2016YED0201003)和麗江市科技計劃項目(LJGZZ-2018001)


Variation Law and Prediction Model of Substrate Moisture Content at Different Depths
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    摘要:

    為探明不同深度的基質(zhì)含水率變化規(guī)律,使用干燥法分別對多個EC-5型傳感器進(jìn)行校準(zhǔn),并將4個傳感器分別放置垂向距滴頭5、10、15、20cm 4個不同深度處,測量不同滴頭流量及滴灌量條件下垂向基質(zhì)含水率的變化,建立了不同深度基質(zhì)含水率預(yù)測模型。試驗結(jié)果表明,在滴灌開始后第1層(距滴頭5cm處)基質(zhì)含水率最先上升并迅速達(dá)到較高水平,滴灌停止后水分將快速擴散至更深基質(zhì)層,其含水率可提升至根系易利用水平(25.3%及以上),水分快速運移時間持續(xù)1h左右,隨著初始基質(zhì)含水率的降低,在相同滴頭流量及灌溉量條件下,水分在垂直方向的運移程度更深,將第1層基質(zhì)初始含水率、滴灌時間、預(yù)測時間、預(yù)測層高度差、滴頭流量作為輸入,利用遺傳算法優(yōu)化的BP神經(jīng)網(wǎng)絡(luò)算法與隨機森林回歸算法(RFR),建立滴灌下基質(zhì)不同深度含水率預(yù)測模型。將試驗所預(yù)測的滴灌后基質(zhì)含水率與實際測量的不同深度基質(zhì)含水率進(jìn)行對比分析,并對不同預(yù)測深度的預(yù)測結(jié)果進(jìn)行誤差分析,結(jié)果表明GA-BP預(yù)測模型及RFR預(yù)測模型的R2分別為0.8664、0.9465,即RFR算法建立的預(yù)測模型更加精確,并且預(yù)測深度越接近于第1層基質(zhì)預(yù)測結(jié)果越準(zhǔn)確。

    Abstract:

    In order to ascertain the change law of the substrate moisture content at different depths, drying method was used to calibrate multiple EC-5 sensors, and the four sensors were placed at four different depths, i.e., 5cm, 10cm, 15cm and 20cm vertically from the dripper. The changes of the vertical substrate water content under different dripper flow and drip irrigation conditions were measured, and a prediction model of substrate water content at different depths was established. The test results showed that the substrate moisture content of the first layer (5cm away from the dripper) was risen first after the drip irrigation started and quickly reached a higher level. After the drip irrigation stopped, the moisture would quickly diffuse to the deeper substrate layer, and its moisture content can be increased to the root system easy to use level (25.3% and above), the rapid water migration time lasted for about 1h. With the decrease of the initial substrate moisture content, under the same dripper flow and irrigation conditions, the degree of water migration in the vertical direction was deeper. The initial water content of the first layer of the substrate, drip irrigation time, prediction time, predicted layer height difference, and dripper flow were used as input, and genetic algorithm optimized BP neural network algorithm and random forest regression algorithm (RFR) were used to establish different depths of water content of the substrate under drip irrigation rate prediction model. The predicted water content of the substrate after drip irrigation in the experiment compared with the actual measured water content of the substrate at different depths, and the error analysis was performed on the prediction results of different prediction depths. The results showed that the prediction accuracy (R2) of the GA-BP prediction model and the RFR prediction model were 0.8664 and 0.9465, respectively, that was, the prediction model established by the RFR algorithm was more accurate, and the closer the prediction depth was to the first layer, the more accurate the prediction result was.

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楊成飛,和壽星,孟繁佳,李文軍,李莉,SIGRIMIS N A.不同深度基質(zhì)含水率變化規(guī)律與預(yù)測模型研究[J].農(nóng)業(yè)機械學(xué)報,2020,51(s2):408-414. YANG Chengfei, HE Shouxing, MENG Fanjia, LI Wenjun, LI Li, SIGRIMIS N A. Variation Law and Prediction Model of Substrate Moisture Content at Different Depths[J]. Transactions of the Chinese Society for Agricultural Machinery,2020,51(s2):408-414.

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  • 收稿日期:2020-08-03
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  • 在線發(fā)布日期: 2020-12-10
  • 出版日期: 2020-12-10
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