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一种简单的共享式多层梯度补给方法 被引量:2
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作者 杜飞 杨云 +1 位作者 胡媛媛 曹丽娟 《软件学报》 EI CSCD 北大核心 2020年第7期2157-2168,共12页
深度学习通过多层特征提取方式,可以将原始复杂数据自动表征为高级抽象特征,该模型具有很强的建模能力,普遍应用于图像识别语音识别、自然语言处理等高复杂问题中.但深度学习由于网络层数深、参数规模庞大,训练时常常会产生梯度消失、... 深度学习通过多层特征提取方式,可以将原始复杂数据自动表征为高级抽象特征,该模型具有很强的建模能力,普遍应用于图像识别语音识别、自然语言处理等高复杂问题中.但深度学习由于网络层数深、参数规模庞大,训练时常常会产生梯度消失、陷入局部最优解、过度拟合等现象.借鉴集成学习的思想,提出一个新颖的深度共享集成网络,该网络通过在深度学习各隐藏层引出多个独立输出层的联合训练的方式,在网络的各层注入梯度,从而对低层隐藏层进行梯度补给,从而降低深度学习中的梯度消失现象,并通过集成多输出层的方式使得整个网络拥有更强的泛化性能. 展开更多
关键词 深度学习 集成学习 堆叠泛化 梯度消失 梯度注入
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New method for plugging channeling in oil field by nitrogen foam
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作者 杨朝蓬 高树生 +3 位作者 岳湘安 吕毓刚 睢宏刚 魏浩光 《Journal of Central South University》 SCIE EI CAS 2014年第2期677-683,共7页
In order to present a new method for plugging channeling in oil field,the injection modes and validity period of foam system which plugged the formation water layer were studied by means of the experimental model whic... In order to present a new method for plugging channeling in oil field,the injection modes and validity period of foam system which plugged the formation water layer were studied by means of the experimental model which simulated the real conditions of oil wells existing channeling.Above all,the influence factors including reservoir pressure,permeability,oil saturation and gas-to-liquid ratio were studied through dynamic experiment.Then,in light of the technology characteristics of foam injection in oil field,the comparison between gas-liquid and liquid-gas injection modes was studied.The result shows that the gas-liquid injection mode can ensure the foam injectivity and plugging performance.The plugging validity of nitrogen foam injected into the formation water layer was evaluated in different plugging pressure gradients by the dynamic method which is more reasonable than the static evaluation method in laboratory.The research demonstrates that the plugging validity period of foam decreases with plugging pressure gradient increasing.If the plugging pressure gradient is 0.15 MPa/m,the validity period is 160 h.Finally,a empirical equation and a plate about the plugging validity and the plugging pressure gradient were obtained for forecasting the validity period of foam. 展开更多
关键词 foam system plugging performance CHANNELING injection mode plugging validity
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