The 2 ℃ warming target has been used widely in global and regional climate change research. Previous studies have shown large uncertainties in the time when surface air temperature （SAT） change over China will reac...The 2 ℃ warming target has been used widely in global and regional climate change research. Previous studies have shown large uncertainties in the time when surface air temperature （SAT） change over China will reach 2℃ rela- tive to the pre-industrial era. To understand the uncertainties, we analyzed the projected SAT in the twenty-first century using 40 state-of-the-art climate models under two Repre- sentative Concentration Pathways （RCP4.5 and RCPS.5） from the Coupled Model Intercomparison Project Phase 5. The 2℃ threshold-crossing time （TCT） of SAT averaged across China was around 2033 and 2029 for RCP4.5 and RCP8.5, respectively. Considering a 4-1o- range of inter- model SAT change, the upper and lower bounds of the 2 ℃ TCT could differ by about 25 years or even more. Uncer- tainty in the projected SAT and the warming rate around the TCT are the two main factors responsible for the TCT uncertainty. The former is determined by the climate sensi- tivity represented by the global mean surface temperature response. About 45 % of the intermodel variance of the projected 2 ~C TCT for averaged SAT over China can be explained by climate sensitivity across the models, which is contributed mainly by central and southern China. In a cli- mate more sensitive to CO2 forcing, stronger greenhouse effect, less stratus cloud over the East Asian monsoon region, and less snow cover on the Tibetan Plateau result in increased downward longwave radiation, increased shortwave radia- tion, and decreased shortwave radiation reflected by the surface, respectively, all of which may advance the TCT.展开更多
智能化科研(AI4R)是科研方法的重大变革。提出科技界不仅要关注科学智能(AI for Science,AI4S),更要重视技术智能(AI for Technology,AI4T);不仅要关注大语言模型(LLM),更要重视大科学模型(LSM)。同时提出,人工智能的突破主要不是靠大算...智能化科研(AI4R)是科研方法的重大变革。提出科技界不仅要关注科学智能(AI for Science,AI4S),更要重视技术智能(AI for Technology,AI4T);不仅要关注大语言模型(LLM),更要重视大科学模型(LSM)。同时提出,人工智能的突破主要不是靠大算力,而是计算模型的转变,中国应当争取在基础模型上做出颠覆性的创新;智能化科研适合做复杂问题的组合搜索,神经网络模型也许已接近能处理困难问题的复杂度阈值点;智能化科研的一种趋势是放弃绝对性,拥抱不确定性,一定时期内要适当容忍“黑盒模型”。展开更多
Based on the diversity of the agricultural system, this research calculates the planting structures of rice, maize and soybean considering the optimal economic-social-ecological aspects. Then, based on the uncertainty...Based on the diversity of the agricultural system, this research calculates the planting structures of rice, maize and soybean considering the optimal economic-social-ecological aspects. Then, based on the uncertainty and randomness of the water resources system,the interval two-stage stochastic programming method,which introduces the uncertainty of the interval number, is used to calculate the groundwater exploitation and the use efficiency of surface water. The method considers the minimum cost of water as the objective of the uncertainty model for surface water and groundwater joint scheduling optimization for different planting structures. Finally, by calculating harmonious entropy, the optimal exploitation utilization interval of surface water and groundwater is determined for optimal cultivation in the Sanjiang Plain.The optimal matching of the planting structure under the economic system is suitable when the mining ratio of the surface is in 44.13%–45.45% and the exploitation utilization of groundwater is in 54.82%–66.86%, the optimal planting structure under the social system is suitable when surface water mining ratio is in 47.84%–48.04% and the groundwater exploitation threshold is in 67.07%–72.00%. This article optimizes the economicsocial-ecological-water system, which is important for the development of a water- and food-conserving society and providing a more accurate management environment.展开更多
In recent years,with the increasing attention paid to climate risks,the changes in climate policies are also more full of uncertainties,which have brought tremendous impact to economic entities,including companies.Usi...In recent years,with the increasing attention paid to climate risks,the changes in climate policies are also more full of uncertainties,which have brought tremendous impact to economic entities,including companies.Using the dynamic threshold model,this study investigates the nonlinear and the asymmetric effect of climate policy uncertainty on Chinese firm investment decisions with panel data of 128 Chinese energy-related companies from 2007 to 2019.The empirical findings indicate that the influence of climate policy uncertainty on firm investment is significantly nonlinear.Overall,climate policy uncertainty is not apparently related to corporate investments in the high-level range,while it negatively affects the investments in the low-level range.In addition,to be more specific,the negative impact of climate policy uncertainty on the mining industry is tremendous,while the influence on the production and supply of electricity,heat,gas,and water sector is remarkably positive.The results of this study could help the company managers and policymakers to arrange appropriate related strategies under different climate policy conditions.展开更多
在实际分类决策中,序贯三支决策模型为决策者提供了一个渐进式的决策方法.然而,现有序贯三支决策模型的研究从提高分类精度或减少不确定性的动机来求取每一粒层的决策阈值,缺乏对二者的综合考虑.为了解决这个问题,本文结合博弈论的思想...在实际分类决策中,序贯三支决策模型为决策者提供了一个渐进式的决策方法.然而,现有序贯三支决策模型的研究从提高分类精度或减少不确定性的动机来求取每一粒层的决策阈值,缺乏对二者的综合考虑.为了解决这个问题,本文结合博弈论的思想构建了基于错误分类率与边界域不确定性博弈的序贯三支决策模型.首先,分析了序贯三支决策模型中边界域不确定性与决策区域错误分类率的变化关系并构建了二者之间的博弈;其次,从博弈终止的条件出发,基于纯策略纳什均衡原理,提出了求取每一粒层自适应决策阈值的优化模型;再次,为了比较不同模型的效果,从多目标决策的角度,设计了基于TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution)的阈值选取方法;最后,通过UCI数据集进行了两种模型的对比实验.实验结果表明:基于博弈论的序贯三支决策模型求取的决策阈值具有更小的错误分类率以及更合理的阈值结构.展开更多
基金supported jointly by the ‘‘Strategic Priority Research Program–Climate Change: Carbon Budget and Related Issues’’ of the Chinese Academy of Sciences (XDA05110300)the Research Fund for Commonwealth Trades (Meteorology) (GYHY201506012)+1 种基金the National Natural Science Foundation of China (41420104006)the China Postdoctoral Science Foundation (2015M581152)
文摘The 2 ℃ warming target has been used widely in global and regional climate change research. Previous studies have shown large uncertainties in the time when surface air temperature （SAT） change over China will reach 2℃ rela- tive to the pre-industrial era. To understand the uncertainties, we analyzed the projected SAT in the twenty-first century using 40 state-of-the-art climate models under two Repre- sentative Concentration Pathways （RCP4.5 and RCPS.5） from the Coupled Model Intercomparison Project Phase 5. The 2℃ threshold-crossing time （TCT） of SAT averaged across China was around 2033 and 2029 for RCP4.5 and RCP8.5, respectively. Considering a 4-1o- range of inter- model SAT change, the upper and lower bounds of the 2 ℃ TCT could differ by about 25 years or even more. Uncer- tainty in the projected SAT and the warming rate around the TCT are the two main factors responsible for the TCT uncertainty. The former is determined by the climate sensi- tivity represented by the global mean surface temperature response. About 45 % of the intermodel variance of the projected 2 ~C TCT for averaged SAT over China can be explained by climate sensitivity across the models, which is contributed mainly by central and southern China. In a cli- mate more sensitive to CO2 forcing, stronger greenhouse effect, less stratus cloud over the East Asian monsoon region, and less snow cover on the Tibetan Plateau result in increased downward longwave radiation, increased shortwave radia- tion, and decreased shortwave radiation reflected by the surface, respectively, all of which may advance the TCT.
文摘智能化科研(AI4R)是科研方法的重大变革。提出科技界不仅要关注科学智能(AI for Science,AI4S),更要重视技术智能(AI for Technology,AI4T);不仅要关注大语言模型(LLM),更要重视大科学模型(LSM)。同时提出,人工智能的突破主要不是靠大算力,而是计算模型的转变,中国应当争取在基础模型上做出颠覆性的创新;智能化科研适合做复杂问题的组合搜索,神经网络模型也许已接近能处理困难问题的复杂度阈值点;智能化科研的一种趋势是放弃绝对性,拥抱不确定性,一定时期内要适当容忍“黑盒模型”。
基金supported by funds from National Natural Science Foundation of China (51179032, 51479032, 51579044)Yangtze River Scholars in Universities of Heilongjiang Province and Water Conservancy Science and Technology Project of Heilongjiang Province (201318, 201503)The Outstanding Youth Fund of Heilongjiang Province (JC201402)
文摘Based on the diversity of the agricultural system, this research calculates the planting structures of rice, maize and soybean considering the optimal economic-social-ecological aspects. Then, based on the uncertainty and randomness of the water resources system,the interval two-stage stochastic programming method,which introduces the uncertainty of the interval number, is used to calculate the groundwater exploitation and the use efficiency of surface water. The method considers the minimum cost of water as the objective of the uncertainty model for surface water and groundwater joint scheduling optimization for different planting structures. Finally, by calculating harmonious entropy, the optimal exploitation utilization interval of surface water and groundwater is determined for optimal cultivation in the Sanjiang Plain.The optimal matching of the planting structure under the economic system is suitable when the mining ratio of the surface is in 44.13%–45.45% and the exploitation utilization of groundwater is in 54.82%–66.86%, the optimal planting structure under the social system is suitable when surface water mining ratio is in 47.84%–48.04% and the groundwater exploitation threshold is in 67.07%–72.00%. This article optimizes the economicsocial-ecological-water system, which is important for the development of a water- and food-conserving society and providing a more accurate management environment.
文摘In recent years,with the increasing attention paid to climate risks,the changes in climate policies are also more full of uncertainties,which have brought tremendous impact to economic entities,including companies.Using the dynamic threshold model,this study investigates the nonlinear and the asymmetric effect of climate policy uncertainty on Chinese firm investment decisions with panel data of 128 Chinese energy-related companies from 2007 to 2019.The empirical findings indicate that the influence of climate policy uncertainty on firm investment is significantly nonlinear.Overall,climate policy uncertainty is not apparently related to corporate investments in the high-level range,while it negatively affects the investments in the low-level range.In addition,to be more specific,the negative impact of climate policy uncertainty on the mining industry is tremendous,while the influence on the production and supply of electricity,heat,gas,and water sector is remarkably positive.The results of this study could help the company managers and policymakers to arrange appropriate related strategies under different climate policy conditions.
文摘在实际分类决策中,序贯三支决策模型为决策者提供了一个渐进式的决策方法.然而,现有序贯三支决策模型的研究从提高分类精度或减少不确定性的动机来求取每一粒层的决策阈值,缺乏对二者的综合考虑.为了解决这个问题,本文结合博弈论的思想构建了基于错误分类率与边界域不确定性博弈的序贯三支决策模型.首先,分析了序贯三支决策模型中边界域不确定性与决策区域错误分类率的变化关系并构建了二者之间的博弈;其次,从博弈终止的条件出发,基于纯策略纳什均衡原理,提出了求取每一粒层自适应决策阈值的优化模型;再次,为了比较不同模型的效果,从多目标决策的角度,设计了基于TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution)的阈值选取方法;最后,通过UCI数据集进行了两种模型的对比实验.实验结果表明:基于博弈论的序贯三支决策模型求取的决策阈值具有更小的错误分类率以及更合理的阈值结构.
