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Prediction Model of Weekly Retail Price for Eggs Based on Chaotic Neural Network 被引量:3
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作者 LI Zhe-min CUI Li-guo +4 位作者 XU Shi-wei weng ling-yun DONG Xiao-xia LI Gan-qiong YU Hai-peng 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2013年第12期2292-2299,共8页
This paper establishes a short-term prediction model of weekly retail prices for eggs based on chaotic neural network with the weekly retail prices of eggs from January 2008 to December 2012 in China.In the process of... This paper establishes a short-term prediction model of weekly retail prices for eggs based on chaotic neural network with the weekly retail prices of eggs from January 2008 to December 2012 in China.In the process of determining the structure of the chaotic neural network,the number of input layer nodes of the network is calculated by reconstructing phase space and computing its saturated embedding dimension,and then the number of hidden layer nodes is estimated by trial and error.Finally,this model is applied to predict the retail prices of eggs and compared with ARIMA.The result shows that the chaotic neural network has better nonlinear fitting ability and higher precision in the prediction of weekly retail price of eggs.The empirical result also shows that the chaotic neural network can be widely used in the field of short-term prediction of agricultural prices. 展开更多
关键词 chaos theory chaotic neural network neural network technology short-term prediction weekly retail price of eggs
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长期不同施氮量下冬小麦-夏玉米复种系统土壤硝态氮累积和淋洗特征 被引量:19
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作者 翁玲云 杨晓卡 +4 位作者 吕敏娟 辛思颖 陈帅 马文奇 魏静 《应用生态学报》 CAS CSCD 北大核心 2018年第8期2551-2558,共8页
冬小麦夏玉米是华北平原主要的粮食作物,其集约化的农业种植体系虽然普遍实现了粮食的高产,但氮肥常年大量施用会造成土壤深层硝态氮累积、淋洗等问题.本文以河北清苑冬小麦-夏玉米复种体系为研究对象,设置不同施氮量(N_0、N_(100)、N_(... 冬小麦夏玉米是华北平原主要的粮食作物,其集约化的农业种植体系虽然普遍实现了粮食的高产,但氮肥常年大量施用会造成土壤深层硝态氮累积、淋洗等问题.本文以河北清苑冬小麦-夏玉米复种体系为研究对象,设置不同施氮量(N_0、N_(100)、N_(180)、N_(255)、N_(330),分别表示施氮0、100、180、255、330 kg·hm^(-2)),于2010—2016年开展6个周期定位试验,研究不同施氮量对土壤硝态氮累积和淋洗的影响.结果表明:在12季冬小麦和夏玉米收获期各处理产量存在显著差异,土壤硝态氮含量表现为冬小麦季累积、夏玉米季淋洗的特点,且90和180 cm土层硝态氮累积量均表现为N_(330)>N_(255)>N_(180)>N_(100_)>N_0.从土壤剖面分布看,硝态氮可淋洗至990 cm的深层土壤中,且出现6个累积峰,同时土壤硝态氮累积峰随施氮量增加而下移,N330处理累积峰最深在840 cm处.从各土层累积量的分配看,5个处理0~90 cm硝态氮累积量占比在10%左右,大部分都在90 cm以下,不能被植物利用.可见,夏玉米季硝态氮淋洗严重,施氮量越高,土壤硝态氮残留量越大,向土壤深层淋洗量也越多,由此带来的对地下水的污染风险应该引起重视.从产量与硝态氮累积情况来看,N_(180)为最优处理. 展开更多
关键词 施氮量 硝态氮 累积 淋洗 长期试验 冬小麦-夏玉米复种系统
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