This paper studied a structured model by age of tuberculosis. A population divided into two parts was considered for the study. Each subpopulation is submitted to a program of vaccination. It was allowed the migration...This paper studied a structured model by age of tuberculosis. A population divided into two parts was considered for the study. Each subpopulation is submitted to a program of vaccination. It was allowed the migration of vaccinated people only between the two patches. After the determination of and , the local and global stability of the disease-free equilibrium was studied. It showed the existence of three endemic equilibrium points. The theoretical results were illustrated by a numeric simulation.展开更多
探讨土地利用变化所引发的水质净化演变,对于保护和改善水质,实现可持续发展具有重要意义。以“两湖一库”流域为例,运用PLUS(patch-level land use simulation)模型和InVEST(integrated valuation of ecosystem services and tradeoffs...探讨土地利用变化所引发的水质净化演变,对于保护和改善水质,实现可持续发展具有重要意义。以“两湖一库”流域为例,运用PLUS(patch-level land use simulation)模型和InVEST(integrated valuation of ecosystem services and tradeoffs)模型生态系统服务水质净化模块,基于2000年、2010年和2020年土地利用数据,模拟流域在未来自然发展情景和生态保护情景下的用地类型时空格局变化以及水质净化特征。定量揭示土地利用变化与水质净化功能的响应关系。结果表明:“两湖一库”流域土地类型以耕地为主,2030年在自然发展情景下耕地、林地、草地面积呈下降趋势,建设用地呈上升趋势,生态保护情景可有效保护流域耕地、林地等空间分布和面积;“两湖一库”流域TN、TP输出量以低强度输出为主,2000—2020年TN输出量先增加后减少,TP输出量逐年增加,水质净化能力呈稳中变好的趋势;2030年自然发展情境下TN输出量持续减少,TP输出量呈向上浮动,生态保护情景下TN、TP输出量较自然发展情景下减少,生态保护情景可以增加水质净化能力。生态用地类型可以有效截留N、P进入水体,生态保护情景下有效降低生态用地类型的变化速度,减少TN、TP的输出量,“两湖一库”流域未来规划中应增加生态用地的占比,增加土地类型对TN、TP的截留能力。展开更多
目的图像超分辨率算法在实际应用中有着较为广泛的需求和研究。然而传统基于样本的超分辨率算法均使用简单的图像梯度特征表征低分辨率图像块,这些特征难以有效地区分不同的低分辨率图像块。针对此问题,在传统基于样本超分辨率算法的基...目的图像超分辨率算法在实际应用中有着较为广泛的需求和研究。然而传统基于样本的超分辨率算法均使用简单的图像梯度特征表征低分辨率图像块,这些特征难以有效地区分不同的低分辨率图像块。针对此问题,在传统基于样本超分辨率算法的基础上,提出双通道卷积神经网络学习低分辨率与高分辨率图像块相似度进行图像超分辨率的算法。方法首先利用深度卷积神经网络学习得到有效的低分辨率与高分辨率图像块之间相似性度量,然后根据输入低分辨率图像块与高分辨率图像块字典基元的相似度重构出对应的高分辨率图像块。结果本文算法在Set5和Set14数据集上放大3倍情况下分别取得了平均峰值信噪比(PSNR)为32.53 d B与29.17 d B的效果。结论本文算法从低分辨率与高分辨率图像块相似度学习角度解决图像超分辨率问题,可以更好地保持结果图像中的边缘信息,减弱结果中的振铃现象。本文算法可以很好地适用于自然场景图像的超分辨率增强任务。展开更多
Projection models are commonly used to evaluate the impacts of fishing.However,previously developed projection tools were not suitable for China’s fisheries as they are either overly complex and data-demanding or too...Projection models are commonly used to evaluate the impacts of fishing.However,previously developed projection tools were not suitable for China’s fisheries as they are either overly complex and data-demanding or too simple to reflect the realistic management measures.Herein,an intermediate-complexity projection model was developed that could adequately describe fish population dynamics and account for management measures including mesh size limits,summer closure,and spatial closure.A two-patch operating model was outlined for the projection model and applied to the heavily depleted but commercially important small yellow croaker(Larimichthys polyactis)fishery in the Haizhou Bay,China,as a case study.The model was calibrated to realistically capture the fisheries dynamics with hindcasting.Three simulation scenarios featuring different fishing intensities based on status quo and maximum sustainable yield(MSY)were proposed and evaluated with projections.Stochastic projections were additionally performed to investigate the influence of uncertainty associated with recruitment strengths and the implementation of control targets.It was found that fishing at FMSY level could effectively rebuild the depleted stock biomass,while the stock collapsed rapidly in the status quo scenario.Uncertainty in recruitment and implementation could result in variabilities in management effects;but they did not much alter the management effects of the FMSY scenario.These results indicate that the lack of science-based control targets in fishing mortality or catch limits has hindered the achievement of sustainable fisheries in China.Overall,the presented work highlights that the developed projection model can promote the understanding of the possible consequences of fishing under uncertainty and is applicable to other fisheries in China.展开更多
文摘This paper studied a structured model by age of tuberculosis. A population divided into two parts was considered for the study. Each subpopulation is submitted to a program of vaccination. It was allowed the migration of vaccinated people only between the two patches. After the determination of and , the local and global stability of the disease-free equilibrium was studied. It showed the existence of three endemic equilibrium points. The theoretical results were illustrated by a numeric simulation.
文摘探讨土地利用变化所引发的水质净化演变,对于保护和改善水质,实现可持续发展具有重要意义。以“两湖一库”流域为例,运用PLUS(patch-level land use simulation)模型和InVEST(integrated valuation of ecosystem services and tradeoffs)模型生态系统服务水质净化模块,基于2000年、2010年和2020年土地利用数据,模拟流域在未来自然发展情景和生态保护情景下的用地类型时空格局变化以及水质净化特征。定量揭示土地利用变化与水质净化功能的响应关系。结果表明:“两湖一库”流域土地类型以耕地为主,2030年在自然发展情景下耕地、林地、草地面积呈下降趋势,建设用地呈上升趋势,生态保护情景可有效保护流域耕地、林地等空间分布和面积;“两湖一库”流域TN、TP输出量以低强度输出为主,2000—2020年TN输出量先增加后减少,TP输出量逐年增加,水质净化能力呈稳中变好的趋势;2030年自然发展情境下TN输出量持续减少,TP输出量呈向上浮动,生态保护情景下TN、TP输出量较自然发展情景下减少,生态保护情景可以增加水质净化能力。生态用地类型可以有效截留N、P进入水体,生态保护情景下有效降低生态用地类型的变化速度,减少TN、TP的输出量,“两湖一库”流域未来规划中应增加生态用地的占比,增加土地类型对TN、TP的截留能力。
文摘目的图像超分辨率算法在实际应用中有着较为广泛的需求和研究。然而传统基于样本的超分辨率算法均使用简单的图像梯度特征表征低分辨率图像块,这些特征难以有效地区分不同的低分辨率图像块。针对此问题,在传统基于样本超分辨率算法的基础上,提出双通道卷积神经网络学习低分辨率与高分辨率图像块相似度进行图像超分辨率的算法。方法首先利用深度卷积神经网络学习得到有效的低分辨率与高分辨率图像块之间相似性度量,然后根据输入低分辨率图像块与高分辨率图像块字典基元的相似度重构出对应的高分辨率图像块。结果本文算法在Set5和Set14数据集上放大3倍情况下分别取得了平均峰值信噪比(PSNR)为32.53 d B与29.17 d B的效果。结论本文算法从低分辨率与高分辨率图像块相似度学习角度解决图像超分辨率问题,可以更好地保持结果图像中的边缘信息,减弱结果中的振铃现象。本文算法可以很好地适用于自然场景图像的超分辨率增强任务。
基金The Fund of the China Scholarship Council under contract Nos 201806330043 and 201806330042the Marine Science and Technology Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2018SDKJ0501-2the National Key Research and Development Program of China under contract Nos2018YFD0900904 and 2018YFD0900906。
文摘Projection models are commonly used to evaluate the impacts of fishing.However,previously developed projection tools were not suitable for China’s fisheries as they are either overly complex and data-demanding or too simple to reflect the realistic management measures.Herein,an intermediate-complexity projection model was developed that could adequately describe fish population dynamics and account for management measures including mesh size limits,summer closure,and spatial closure.A two-patch operating model was outlined for the projection model and applied to the heavily depleted but commercially important small yellow croaker(Larimichthys polyactis)fishery in the Haizhou Bay,China,as a case study.The model was calibrated to realistically capture the fisheries dynamics with hindcasting.Three simulation scenarios featuring different fishing intensities based on status quo and maximum sustainable yield(MSY)were proposed and evaluated with projections.Stochastic projections were additionally performed to investigate the influence of uncertainty associated with recruitment strengths and the implementation of control targets.It was found that fishing at FMSY level could effectively rebuild the depleted stock biomass,while the stock collapsed rapidly in the status quo scenario.Uncertainty in recruitment and implementation could result in variabilities in management effects;but they did not much alter the management effects of the FMSY scenario.These results indicate that the lack of science-based control targets in fishing mortality or catch limits has hindered the achievement of sustainable fisheries in China.Overall,the presented work highlights that the developed projection model can promote the understanding of the possible consequences of fishing under uncertainty and is applicable to other fisheries in China.
