连续时序的叶面积指数(Leaf Area Index,LAI)可反映苜蓿长势的变化情况,预测苜蓿未来时段的LAI对指导田间管理决策具有重要作用。针对LAI数据采集困难,导致苜蓿时序LAI存在训练数据不足的问题,该文以生长天数为自变量,采用修正的Logisti...连续时序的叶面积指数(Leaf Area Index,LAI)可反映苜蓿长势的变化情况,预测苜蓿未来时段的LAI对指导田间管理决策具有重要作用。针对LAI数据采集困难,导致苜蓿时序LAI存在训练数据不足的问题,该文以生长天数为自变量,采用修正的Logistic模型对实测苜蓿LAI变化的动态过程进行建模,根据LAI模拟曲线进行数据插补,从而构建宁夏引黄灌区试验区3年的逐日苜蓿LAI数据集。在插补数据集的基础上,为解决苜蓿刈割后数据突变问题,提出了一种ME-BiLSTM模型。该模型集成移动累计和检验方法(MOSUM)以及基于双向长短期记忆网络(BiLSTM)的编码器-解码器神经网络。MOSUM方法可以实现LAI数据集中突变点检测,并剔除包含突变点训练批次,同时应用改进的BiLSTM模型进行预测。结果表明:ME-BiLSTM模型能较好地进行苜蓿LAI未来曲线变化的预测,其决定系数(R^(2))、均方根误差(RMSE)值分别为0.9985和0.0722。对于苜蓿生长的各个茬次,预测模型对于第1茬、第4茬的预测精度最高,第2茬和第3茬的预测精度稍有降低。展开更多
Feline panleukopenia virus (FPV),belonging to the genus Parvovirus within the family Parvoviridae, infects and causes disease in carnivore species throughout the world. However, few epidemiological studies of this vir...Feline panleukopenia virus (FPV),belonging to the genus Parvovirus within the family Parvoviridae, infects and causes disease in carnivore species throughout the world. However, few epidemiological studies of this virus have been done in wildlife in China. The aims of this study were to determine the infection rate of FPV in captive tigers, lions and domestic cats. Serum samples were obtained from 207 tigers and 4 lions between 2002 and 2006 in different wildlife zoos of China,and 23 domestic cats, and further tested for antibodies against FPV by serum neutralization(SN) assay and hemagglutination-inhibition (HI) assay, whose results are consistent. A seropositive rate of 53.1% was found in tigers,25% in lions and 26% in cats. These results indicated that most of the felines had been infected with feline panleukopenia virus, and the virus may cause disease in carnivore species in China.展开更多
文摘连续时序的叶面积指数(Leaf Area Index,LAI)可反映苜蓿长势的变化情况,预测苜蓿未来时段的LAI对指导田间管理决策具有重要作用。针对LAI数据采集困难,导致苜蓿时序LAI存在训练数据不足的问题,该文以生长天数为自变量,采用修正的Logistic模型对实测苜蓿LAI变化的动态过程进行建模,根据LAI模拟曲线进行数据插补,从而构建宁夏引黄灌区试验区3年的逐日苜蓿LAI数据集。在插补数据集的基础上,为解决苜蓿刈割后数据突变问题,提出了一种ME-BiLSTM模型。该模型集成移动累计和检验方法(MOSUM)以及基于双向长短期记忆网络(BiLSTM)的编码器-解码器神经网络。MOSUM方法可以实现LAI数据集中突变点检测,并剔除包含突变点训练批次,同时应用改进的BiLSTM模型进行预测。结果表明:ME-BiLSTM模型能较好地进行苜蓿LAI未来曲线变化的预测,其决定系数(R^(2))、均方根误差(RMSE)值分别为0.9985和0.0722。对于苜蓿生长的各个茬次,预测模型对于第1茬、第4茬的预测精度最高,第2茬和第3茬的预测精度稍有降低。
文摘Feline panleukopenia virus (FPV),belonging to the genus Parvovirus within the family Parvoviridae, infects and causes disease in carnivore species throughout the world. However, few epidemiological studies of this virus have been done in wildlife in China. The aims of this study were to determine the infection rate of FPV in captive tigers, lions and domestic cats. Serum samples were obtained from 207 tigers and 4 lions between 2002 and 2006 in different wildlife zoos of China,and 23 domestic cats, and further tested for antibodies against FPV by serum neutralization(SN) assay and hemagglutination-inhibition (HI) assay, whose results are consistent. A seropositive rate of 53.1% was found in tigers,25% in lions and 26% in cats. These results indicated that most of the felines had been infected with feline panleukopenia virus, and the virus may cause disease in carnivore species in China.