针对误差逆向传播 BP ( back propagation)神经网络在 GNSS 水准拟合中存在梯度消失、陷于局部最小点的问题,通过使用深度学习中的分段线性整流函数Relu( rectified linear units)作为神经元激活函数,自适应矩估计Adam ( adaptive momen...针对误差逆向传播 BP ( back propagation)神经网络在 GNSS 水准拟合中存在梯度消失、陷于局部最小点的问题,通过使用深度学习中的分段线性整流函数Relu( rectified linear units)作为神经元激活函数,自适应矩估计Adam ( adaptive moment estimation)算法作为网络优化函数,提出了一种基于深度学习的 BP 神经网络模型。研究结果表明:改进后的 BP 神经网络内外符合精度分别提高近 50%和 25%,可达 0. 9 cm 和 2. 4 cm,为 GNSS 水准拟合提供了新的思路。展开更多
Plastic waste and debris have caused substantial environmental pollution globally in the past decades,and they have been accumulated in hundreds of terrestrial and aquatic avian species.Birds are susceptible and vulne...Plastic waste and debris have caused substantial environmental pollution globally in the past decades,and they have been accumulated in hundreds of terrestrial and aquatic avian species.Birds are susceptible and vulnerable to external environments;therefore,they could be used to estimate the negative effects of environmental pollution.In this review,we summarize the effects of macroplastics,microplastics,and plastic-derived additives and plastic-absorbed chemicals on birds.First,macroplastics and microplastics accumulate in different tissues of various aquatic and terrestrial birds,suggesting that birds could suffer from the macroplastics and microplastics-associated contaminants in the aquatic and terrestrial environments.Second,the detrimental effects of macroplastics and microplastics,and their derived additives and absorbed chemicals on the individual survival,growth and development,reproductive output,and physiology,are summarized in different birds,as well as the known toxicological mechanisms of plastics in laboratory model mammals.Finally,we identify that human commensal birds,long-life-span birds,and model bird species could be utilized to different research objectives to evaluate plastic pollution burden and toxicological effects of chronic plastic exposure.展开更多
文摘针对误差逆向传播 BP ( back propagation)神经网络在 GNSS 水准拟合中存在梯度消失、陷于局部最小点的问题,通过使用深度学习中的分段线性整流函数Relu( rectified linear units)作为神经元激活函数,自适应矩估计Adam ( adaptive moment estimation)算法作为网络优化函数,提出了一种基于深度学习的 BP 神经网络模型。研究结果表明:改进后的 BP 神经网络内外符合精度分别提高近 50%和 25%,可达 0. 9 cm 和 2. 4 cm,为 GNSS 水准拟合提供了新的思路。
基金supported by the National Natural Science Foundation of China(NSFC,31971413)the Natural Science Foundation of Hebei Province(NSFHB,C2020205038)to DL+3 种基金the NSFHB(C2020205005)the Foundation of Hebei Normal University(17116027)the Postdoctoral Research Foundation of China(PRFC,2020M670685)to LWthe PRFC(2020M680902)to LY。
文摘Plastic waste and debris have caused substantial environmental pollution globally in the past decades,and they have been accumulated in hundreds of terrestrial and aquatic avian species.Birds are susceptible and vulnerable to external environments;therefore,they could be used to estimate the negative effects of environmental pollution.In this review,we summarize the effects of macroplastics,microplastics,and plastic-derived additives and plastic-absorbed chemicals on birds.First,macroplastics and microplastics accumulate in different tissues of various aquatic and terrestrial birds,suggesting that birds could suffer from the macroplastics and microplastics-associated contaminants in the aquatic and terrestrial environments.Second,the detrimental effects of macroplastics and microplastics,and their derived additives and absorbed chemicals on the individual survival,growth and development,reproductive output,and physiology,are summarized in different birds,as well as the known toxicological mechanisms of plastics in laboratory model mammals.Finally,we identify that human commensal birds,long-life-span birds,and model bird species could be utilized to different research objectives to evaluate plastic pollution burden and toxicological effects of chronic plastic exposure.
