Single stage and double stage interrupted hot compression tests for physical simulating hot rolling have been carried out on the THERMECMATSTOR Z simulator for 00Cr20Ni18Mo6Cu[N] austenitic stainless steel under high ...Single stage and double stage interrupted hot compression tests for physical simulating hot rolling have been carried out on the THERMECMATSTOR Z simulator for 00Cr20Ni18Mo6Cu[N] austenitic stainless steel under high temperature (1223～1373 K) and various strain rates (0.1～60 s -1 ). The high temperature mechanical behaviors and microstructure evolution of the steel were studied. The activation energies of hot deformation and dynamic, static and metadynamic recrystallization were calculated. Serials of perfect flow stress model considering dynamic recrystallization were established. The predicted result by the model was well agreed with the experiment data. The kinetics of metadynamic and static recrystallization had also been determined.展开更多
In 2021,China updated its nationally determined contributions(NDCs)under the Paris Agreement,which prompts a more accurate mea-surement of its emissions inventory and a reasonable pathway toward carbon neutrality by 2...In 2021,China updated its nationally determined contributions(NDCs)under the Paris Agreement,which prompts a more accurate mea-surement of its emissions inventory and a reasonable pathway toward carbon neutrality by 2060.This study reviews the estimates using the bottom-up emissions factor method or the top-down atmospheric CO_(2) concentration inversion method to derive China's CO_(2) emissions inventory and finds that CO_(2) emissions from energy combustion and industrial processes in Chinese mainland range from 11.3-12.0 GtCO_(2) in 2021.Based on a comprehensive review of pathways proposed by domestic and international studies and an analysis of the origins of their differences,we proposed the Tsinghua-CMA pathway that coordinates the 2℃global temperature rise control target with China's current CO_(2) emissions status and mitigation policies.The pathway requires China's CO_(2) emissions to peak around 2028-2029 at about 12.8 GtCO_(2),then decline steadily to about 11.2 GtCO_(2) in 2035,3.6 GtCO_(2) in 2050,and 0.9 GtCO_(2) in 2060.Compared to a reference scenario without updated NDCs,this pathway would result in an economic cost of about 0.9%cumulative GDP between 2020 and 2060,only 1/4-1/3 of the cost associated with pathways that align with the 1.5℃target.We recommended that China improves emissions accounting by cross-validating bottom-up and top-down approaches and regularly updating the pathway toward carbon neutrality while maintaining consistency with its evolving CO_(2) emissions inventory,policy trends,and global CO_(2) emission budget updates.展开更多
The 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories added the method of assimilating atmospheric CO_(2) concentrations to invert carbon sources and sinks;however,many global carbon ...The 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories added the method of assimilating atmospheric CO_(2) concentrations to invert carbon sources and sinks;however,many global carbon inversion models are not publicly available.In addition,our regional assimilation inversion system,CCMVS-R(China Carbon Monitoring,Verification and Supporting for Regional),needs a global carbon inversion model with higher assimilation efficiency to provide boundary conditions.Here,an inversion model based on the global atmospheric chemistry model GEOS-Chem and a more accurate and easier-to-implement ensemble square root Kalman filter(EnSRF)algorithm is constructed and used to infer global and China's carbon fluxes in 2019.Atmospheric CO_(2) concentrations from ObsPack sites and five additional CO_(2) observational sites from China's Greenhouse Gas Observation Network(CGHGNET)were used for data assimilation to improve the estimate.The inverted annual global terrestrial and oceanic carbon uptake is 2.12 and 2.53 Pg C per year,respectively,accounting for 21.1%and 25.1%of global fossil fuel CO_(2) emissions.The remaining 5.41 Pg C per year in the atmosphere is consistent with the global atmospheric CO_(2) growth rates of 5.44 Pg C per year reported by the National Oceanic and Atmospheric Administration(NOAA),showing that the inversion model can provide a reasonable estimate of global-scale natural carbon sinks.The inverted terrestrial carbon sink of China is 0.37 Pg C per year,accounting for approximately 13%of China's fossil CO_(2) emissions.展开更多
基金Supported by National Natural Science Foundation of China!( 5 95 71 0 6 5 )
文摘Single stage and double stage interrupted hot compression tests for physical simulating hot rolling have been carried out on the THERMECMATSTOR Z simulator for 00Cr20Ni18Mo6Cu[N] austenitic stainless steel under high temperature (1223～1373 K) and various strain rates (0.1～60 s -1 ). The high temperature mechanical behaviors and microstructure evolution of the steel were studied. The activation energies of hot deformation and dynamic, static and metadynamic recrystallization were calculated. Serials of perfect flow stress model considering dynamic recrystallization were established. The predicted result by the model was well agreed with the experiment data. The kinetics of metadynamic and static recrystallization had also been determined.
基金supported by the Special Project (42341202 and 72140005)of the National Natural Science Foundation of China,Pathways to Achieve Carbon Neutrality。
文摘In 2021,China updated its nationally determined contributions(NDCs)under the Paris Agreement,which prompts a more accurate mea-surement of its emissions inventory and a reasonable pathway toward carbon neutrality by 2060.This study reviews the estimates using the bottom-up emissions factor method or the top-down atmospheric CO_(2) concentration inversion method to derive China's CO_(2) emissions inventory and finds that CO_(2) emissions from energy combustion and industrial processes in Chinese mainland range from 11.3-12.0 GtCO_(2) in 2021.Based on a comprehensive review of pathways proposed by domestic and international studies and an analysis of the origins of their differences,we proposed the Tsinghua-CMA pathway that coordinates the 2℃global temperature rise control target with China's current CO_(2) emissions status and mitigation policies.The pathway requires China's CO_(2) emissions to peak around 2028-2029 at about 12.8 GtCO_(2),then decline steadily to about 11.2 GtCO_(2) in 2035,3.6 GtCO_(2) in 2050,and 0.9 GtCO_(2) in 2060.Compared to a reference scenario without updated NDCs,this pathway would result in an economic cost of about 0.9%cumulative GDP between 2020 and 2060,only 1/4-1/3 of the cost associated with pathways that align with the 1.5℃target.We recommended that China improves emissions accounting by cross-validating bottom-up and top-down approaches and regularly updating the pathway toward carbon neutrality while maintaining consistency with its evolving CO_(2) emissions inventory,policy trends,and global CO_(2) emission budget updates.
基金financially supported by the General Project of Top-Design of Mlti-Scale Nature-Social Models,Data Support and Decision Support System for NSFC Carbon Neutrality Major Project and the Basic Scientific Research Fund of the Chinese Academy of Meteorological Sciences(2021Z014)。
文摘The 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories added the method of assimilating atmospheric CO_(2) concentrations to invert carbon sources and sinks;however,many global carbon inversion models are not publicly available.In addition,our regional assimilation inversion system,CCMVS-R(China Carbon Monitoring,Verification and Supporting for Regional),needs a global carbon inversion model with higher assimilation efficiency to provide boundary conditions.Here,an inversion model based on the global atmospheric chemistry model GEOS-Chem and a more accurate and easier-to-implement ensemble square root Kalman filter(EnSRF)algorithm is constructed and used to infer global and China's carbon fluxes in 2019.Atmospheric CO_(2) concentrations from ObsPack sites and five additional CO_(2) observational sites from China's Greenhouse Gas Observation Network(CGHGNET)were used for data assimilation to improve the estimate.The inverted annual global terrestrial and oceanic carbon uptake is 2.12 and 2.53 Pg C per year,respectively,accounting for 21.1%and 25.1%of global fossil fuel CO_(2) emissions.The remaining 5.41 Pg C per year in the atmosphere is consistent with the global atmospheric CO_(2) growth rates of 5.44 Pg C per year reported by the National Oceanic and Atmospheric Administration(NOAA),showing that the inversion model can provide a reasonable estimate of global-scale natural carbon sinks.The inverted terrestrial carbon sink of China is 0.37 Pg C per year,accounting for approximately 13%of China's fossil CO_(2) emissions.
