After the first concrete was poured on December 9, 2012 at the Shidao Bay site in Rongcheng, Shandong Province, China, the construction of the reactor building for the world＇s first high-temperature gas- cooled react...After the first concrete was poured on December 9, 2012 at the Shidao Bay site in Rongcheng, Shandong Province, China, the construction of the reactor building for the world＇s first high-temperature gas- cooled reactor pebble-bed module （HTR-PM） demonstration power plant was completed in June, 2015. Installation of the main equipment then began, and the power plant is currently progressing well to- ward connecting to the grid at the end of 2017. The thermal power of a single HTR-PM reactor module is 250 MW,h, the helium temperatures at the reactor core inlet/outlet are 250/750 ℃, and a steam of 13.25 MPa/567 ~C is produced at the steam generator outlet. Two HTR-PM reactor modules are connect- ed to a steam turbine to form a 210 MW nuclear power plant. Due to China＇s industrial capability, we were able to overcome great difficulties, manufacture first-of-a-kind equipment, and realize series ma- jor technological innovations. We have achieved successful results in many aspects, including planning and implementing R＆D, establishing an industrial partnership, manufacturing equipment, fuel produc- tion, licensing, site preparation, and balancing safety and economics; these obtained experiences may also be referenced by the global nuclear community.展开更多
In order to understand the role of East Asian subtropical westerly jet (EASWJ) in forecasting summer precipitation in East China,interseasonal pentad characteristics of the EASWJ and their relation to summer precipita...In order to understand the role of East Asian subtropical westerly jet (EASWJ) in forecasting summer precipitation in East China,interseasonal pentad characteristics of the EASWJ and their relation to summer precipitation in East China are analyzed with the daily reanalysis data provided by National Centers for Environmental Prediction (NCEP,USA) and daily precipitation data from 714 Chinese meteorological stations during the period 1960-2009.In addition,the daily evolution of the EASWJ and objective quantification of the EASWJ are investigated for the Meiyu season over the middle and lower reaches of the Yangtze River valley.It is found that the EASWJ and summer precipitation bands in East China move simultaneously.Especially,the stationary state and northward shift of the EASWJ are closely associated with the beginning,ending and stabilization of the annually first raining season in South China and Meiyu over these reaches.Analysis on the characteristics of the EASWJ in typical (atypical) Meiyu years over these reaches shows that the EASWJ swings steadily around its climatological position in meridional orientation (with large amplitude).Numerical experiments on an example in 2005 shows that indexes proposed in this study can depict the EASWJ well and should be valuable for application in the operation.展开更多
Neutron tube is a kind of accelerator neutron source, which has been applied extensively. It is mainly composed of an ion source system, an accelerator system, and a target system. The target system is one of the most...Neutron tube is a kind of accelerator neutron source, which has been applied extensively. It is mainly composed of an ion source system, an accelerator system, and a target system. The target system is one of the most important parameters of the neutron tube and it impacts directly the yield, the lifetime, and the stability. By far the relation between the property of neutron tube and target thickness has not been studied drastically in the Institute of Radiation Technology of Northeast Normal University. High-quality titanium target should be produced in order to manufacture the neutron tube with intense yield, long lifetime and high stability. In our experiment, the pure titanium film was evaporated on the ceramic target by using the evaporation technique. The impact of the thickness of the titanium film on the yield of the neutron tube was studied, and the yield of the neutron tube was on optimistic state if the thickness of titanium film was 2.2 μm. The properties of training and stability of neutron tubes with different thick titanium film target were also present in this paper.展开更多
Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesize...Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesized that there is a critical minimum temperature （CTmin） preventing xylogenesis at treeline. We tested this hypothesis by examining weekly xylogenesis across three and four growing seasons in two natural Smith fir （Abies georgei var. srnithii） treeline sites on the southeastern Tibetan Plateau. Despite differences in the timing of cell differentiation among years, minimum air temperature was the dominant climatic variable associated with xylem growth; the critical minimum temperature （CTmin） for the onset and end of xylogenesis occurred at 0.7 ±0.4 ℃. A process-based modelling chronology of tree-ring formation using this CTmin was consistent with actual tree-ring data. This extremely low CTmin permits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.展开更多
文摘After the first concrete was poured on December 9, 2012 at the Shidao Bay site in Rongcheng, Shandong Province, China, the construction of the reactor building for the world＇s first high-temperature gas- cooled reactor pebble-bed module （HTR-PM） demonstration power plant was completed in June, 2015. Installation of the main equipment then began, and the power plant is currently progressing well to- ward connecting to the grid at the end of 2017. The thermal power of a single HTR-PM reactor module is 250 MW,h, the helium temperatures at the reactor core inlet/outlet are 250/750 ℃, and a steam of 13.25 MPa/567 ~C is produced at the steam generator outlet. Two HTR-PM reactor modules are connect- ed to a steam turbine to form a 210 MW nuclear power plant. Due to China＇s industrial capability, we were able to overcome great difficulties, manufacture first-of-a-kind equipment, and realize series ma- jor technological innovations. We have achieved successful results in many aspects, including planning and implementing R＆D, establishing an industrial partnership, manufacturing equipment, fuel produc- tion, licensing, site preparation, and balancing safety and economics; these obtained experiences may also be referenced by the global nuclear community.
基金Key Project of New technology by China Meteorological Administration (CMATG20092D02)China Public Science and Technology Special Research Projects of Meteorology (GYHY201006007,GYHY201006008,GYHY201006016)National Science and Technology Project (2009BAC51B03)
文摘In order to understand the role of East Asian subtropical westerly jet (EASWJ) in forecasting summer precipitation in East China,interseasonal pentad characteristics of the EASWJ and their relation to summer precipitation in East China are analyzed with the daily reanalysis data provided by National Centers for Environmental Prediction (NCEP,USA) and daily precipitation data from 714 Chinese meteorological stations during the period 1960-2009.In addition,the daily evolution of the EASWJ and objective quantification of the EASWJ are investigated for the Meiyu season over the middle and lower reaches of the Yangtze River valley.It is found that the EASWJ and summer precipitation bands in East China move simultaneously.Especially,the stationary state and northward shift of the EASWJ are closely associated with the beginning,ending and stabilization of the annually first raining season in South China and Meiyu over these reaches.Analysis on the characteristics of the EASWJ in typical (atypical) Meiyu years over these reaches shows that the EASWJ swings steadily around its climatological position in meridional orientation (with large amplitude).Numerical experiments on an example in 2005 shows that indexes proposed in this study can depict the EASWJ well and should be valuable for application in the operation.
文摘Neutron tube is a kind of accelerator neutron source, which has been applied extensively. It is mainly composed of an ion source system, an accelerator system, and a target system. The target system is one of the most important parameters of the neutron tube and it impacts directly the yield, the lifetime, and the stability. By far the relation between the property of neutron tube and target thickness has not been studied drastically in the Institute of Radiation Technology of Northeast Normal University. High-quality titanium target should be produced in order to manufacture the neutron tube with intense yield, long lifetime and high stability. In our experiment, the pure titanium film was evaporated on the ceramic target by using the evaporation technique. The impact of the thickness of the titanium film on the yield of the neutron tube was studied, and the yield of the neutron tube was on optimistic state if the thickness of titanium film was 2.2 μm. The properties of training and stability of neutron tubes with different thick titanium film target were also present in this paper.
基金supported by the National Natural Science Foundations of China(41525001,41661144040,41601204)supported by the Bilateral Project between China and Slovenia(BI-CN/09–11-012)+1 种基金COST Action(FP1106,STRe ESS)supported by the Chinese Academy of Sciences President International Fellowship Initiative for Visiting Scientists(2016VBA074)
文摘Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesized that there is a critical minimum temperature （CTmin） preventing xylogenesis at treeline. We tested this hypothesis by examining weekly xylogenesis across three and four growing seasons in two natural Smith fir （Abies georgei var. srnithii） treeline sites on the southeastern Tibetan Plateau. Despite differences in the timing of cell differentiation among years, minimum air temperature was the dominant climatic variable associated with xylem growth; the critical minimum temperature （CTmin） for the onset and end of xylogenesis occurred at 0.7 ±0.4 ℃. A process-based modelling chronology of tree-ring formation using this CTmin was consistent with actual tree-ring data. This extremely low CTmin permits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.
