1.Introduction 2020 is an unusual year in which the COVID-19 pandemic has raged through the globe,infecting tens of millions of people and killing hundreds of thousands.The pandemic has not only wreaked havoc on publi...1.Introduction 2020 is an unusual year in which the COVID-19 pandemic has raged through the globe,infecting tens of millions of people and killing hundreds of thousands.The pandemic has not only wreaked havoc on public health systems,economic activities,and people's lives,but also has greatly affected and will continue to reshape the world's political,economic,and trade patterns.展开更多
As the world's biggest carbon dioxide(CO_(2))emitter and the largest developing country,China faces daunting challenges to peak its emissions before 2030 and achieve carbon neutrality within 40 years.This study fu...As the world's biggest carbon dioxide(CO_(2))emitter and the largest developing country,China faces daunting challenges to peak its emissions before 2030 and achieve carbon neutrality within 40 years.This study fully considered the carbon-neutrality goal and the temperature rise constraints required by the Paris Agreement,by developing six long-term development scenarios,and conducting a quantitative evaluation on the carbon emissions pathways,energy transformation,technology,policy and investment demand for each scenario.This study combined both bottom-up and top-down methodologies,including simulations and analyses of energy consumption of end-use and power sectors(bottom-up),as well as scenario analysis,investment demand and technology evaluation at the macro level(top-down).This study demonstrates that achieving carbon neutrality before 2060 translates to significant efforts and overwhelming challenges for China.To comply with the target,a high rate of an average annual reduction of CO_(2) emissions by 9.3%from 2030 to 2050 is a necessity,which requires a huge investment demand.For example,in the 1.5℃ scenario,an investment in energy infrastructure alone equivalent to 2.6%of that year's GDP will be necessary.The technological pathway towards carbon neutrality will rely highly on both conventional emission reduction technologies and breakthrough technologies.China needs to balance a long-term development strategy of lower greenhouse gas emissions that meets both the Paris Agreement and the long-term goals for domestic economic and social development,with a phased implementation for both its five-year and long-term plans.展开更多
A number of vision-based methods for detecting laser-induced defects on optical components have been implemented to replace the time-consuming manual inspection.While deep-learning-based methods have achieved state-of...A number of vision-based methods for detecting laser-induced defects on optical components have been implemented to replace the time-consuming manual inspection.While deep-learning-based methods have achieved state-of-the-art performances in many visual recognition tasks,their success often hinges on the availability of a large number of labeled training sets.In this paper,we propose a surface defect detection method based on image segmentation with a U-shaped convolutional network(U-Net).The designed network was trained on paired sets of online and offline images of optics from a large laser facility.We show in our experimental evaluation that our approach can accurately locate laser-induced defects on the optics in real time.The main advantage of the proposed method is that the network can be trained end to end on small samples,without the requirement for manual labeling or manual feature extraction.The approach can be applied to the daily inspection and maintenance of optical components in large laser facilities.展开更多
In this paper,the authors study the moduli space of quasi-polarized complex K3 surfaces of degree 6 and 8 via geometric invariant theory.The general members in such moduli spaces are complete intersections in projecti...In this paper,the authors study the moduli space of quasi-polarized complex K3 surfaces of degree 6 and 8 via geometric invariant theory.The general members in such moduli spaces are complete intersections in projective spaces and they have natural GIT constructions for the corresponding moduli spaces and they show that the K3 surfaces with at worst ADE singularities are GIT stable.They give a concrete description of boundary of the compactification of the degree 6 case via the Hilbert-Mumford criterion.They compute the Picard group via Noether-Lefschetz theory and discuss the connection to the Looijenga’s compactifications from arithmetic perspective.One of the main ingredients is the study of the projective models of K3 surfaces in terms of Noether-Lefschetz divisors.展开更多
基金Thanks for the support of the Special Fund for Global Green Development and Climate Change of Tsinghua University Education Foundation and the Energy Foundation.
文摘1.Introduction 2020 is an unusual year in which the COVID-19 pandemic has raged through the globe,infecting tens of millions of people and killing hundreds of thousands.The pandemic has not only wreaked havoc on public health systems,economic activities,and people's lives,but also has greatly affected and will continue to reshape the world's political,economic,and trade patterns.
文摘As the world's biggest carbon dioxide(CO_(2))emitter and the largest developing country,China faces daunting challenges to peak its emissions before 2030 and achieve carbon neutrality within 40 years.This study fully considered the carbon-neutrality goal and the temperature rise constraints required by the Paris Agreement,by developing six long-term development scenarios,and conducting a quantitative evaluation on the carbon emissions pathways,energy transformation,technology,policy and investment demand for each scenario.This study combined both bottom-up and top-down methodologies,including simulations and analyses of energy consumption of end-use and power sectors(bottom-up),as well as scenario analysis,investment demand and technology evaluation at the macro level(top-down).This study demonstrates that achieving carbon neutrality before 2060 translates to significant efforts and overwhelming challenges for China.To comply with the target,a high rate of an average annual reduction of CO_(2) emissions by 9.3%from 2030 to 2050 is a necessity,which requires a huge investment demand.For example,in the 1.5℃ scenario,an investment in energy infrastructure alone equivalent to 2.6%of that year's GDP will be necessary.The technological pathway towards carbon neutrality will rely highly on both conventional emission reduction technologies and breakthrough technologies.China needs to balance a long-term development strategy of lower greenhouse gas emissions that meets both the Paris Agreement and the long-term goals for domestic economic and social development,with a phased implementation for both its five-year and long-term plans.
文摘A number of vision-based methods for detecting laser-induced defects on optical components have been implemented to replace the time-consuming manual inspection.While deep-learning-based methods have achieved state-of-the-art performances in many visual recognition tasks,their success often hinges on the availability of a large number of labeled training sets.In this paper,we propose a surface defect detection method based on image segmentation with a U-shaped convolutional network(U-Net).The designed network was trained on paired sets of online and offline images of optics from a large laser facility.We show in our experimental evaluation that our approach can accurately locate laser-induced defects on the optics in real time.The main advantage of the proposed method is that the network can be trained end to end on small samples,without the requirement for manual labeling or manual feature extraction.The approach can be applied to the daily inspection and maintenance of optical components in large laser facilities.
基金supported by the National Natural Science Foundation of China(Nos.11771076,11731004,118771155,831013,11890662)National Kay Research and Development Program of China(No.2020YFA0713200)Shanghai Education Commission(No.17SG01).
文摘In this paper,the authors study the moduli space of quasi-polarized complex K3 surfaces of degree 6 and 8 via geometric invariant theory.The general members in such moduli spaces are complete intersections in projective spaces and they have natural GIT constructions for the corresponding moduli spaces and they show that the K3 surfaces with at worst ADE singularities are GIT stable.They give a concrete description of boundary of the compactification of the degree 6 case via the Hilbert-Mumford criterion.They compute the Picard group via Noether-Lefschetz theory and discuss the connection to the Looijenga’s compactifications from arithmetic perspective.One of the main ingredients is the study of the projective models of K3 surfaces in terms of Noether-Lefschetz divisors.
