Using a counterfactual analysis approach, the present paper examines a host of conventional wisdoms relating to issues of farmer, the countryside and agriculture, which are believed to be all originated from the exist...Using a counterfactual analysis approach, the present paper examines a host of conventional wisdoms relating to issues of farmer, the countryside and agriculture, which are believed to be all originated from the existence of mass surplus laborers in China. When analyzing various sources of statistics, evidence shows that there is no longer a large pool of surplus laborers in rural China as most people believe. Based on this counterfactual result, all related events, such as the direction of agricultural technological changes, the level of comparative productivity of agricultural labor, and the degree of rural-urban income gap must be reconsidered.展开更多
The mission objective of Chang’e-3 lunar probe is to achieve our first soft-landing and roving exploration on celestial bodies beyond Earth.On the basis of analyzing technological characteristics in the probe develop...The mission objective of Chang’e-3 lunar probe is to achieve our first soft-landing and roving exploration on celestial bodies beyond Earth.On the basis of analyzing technological characteristics in the probe development,key technology breakthroughs and technological promoting roles of Chang’e-3 are both described.展开更多
Based on patent cooperation data,this study used a range of city network analysis approaches in order to explore the structure of the Chinese city network which is driven by technological knowledge flows.The results r...Based on patent cooperation data,this study used a range of city network analysis approaches in order to explore the structure of the Chinese city network which is driven by technological knowledge flows.The results revealed the spatial structure,composition structure,hierarchical structure,group structure,and control structure of Chinese city network,as well as its dynamic factors.The major findings are:1) the spatial pattern presents a diamond structure,in which Wuhan is the central city;2) although the invention patent knowledge network is the main part of the broader inter-city innovative cooperation network,it is weaker than the utility model patent;3) as the senior level cities,Beijing,Shanghai and the cities in the Zhujiang(Pearl) River Delta Region show a strong capability of both spreading and controlling technological knowledge;4) whilst a national technology alliance has preliminarily formed,regional alliances have not been adequately established;5) even though the cooperation level amongst weak connection cities is not high,such cities still play an important role in the network as a result of their location within ′structural holes′ in the network;and 6) the major driving forces facilitating inter-city technological cooperation are geographical proximity,hierarchical proximity and technological proximity.展开更多
The paper gives an analysis on technical characteristics of repair techniques for friction stir welding defects. To overcome the defects,a new repair technique, inertia friction pull plug welding( IFPPW), was research...The paper gives an analysis on technical characteristics of repair techniques for friction stir welding defects. To overcome the defects,a new repair technique, inertia friction pull plug welding( IFPPW), was researched and its equipment was developed as well. Elementary datum was achieved by investigating the influences of technological parameters on mechanical properties and by analyzing the structural characteristics of repair joint with IFPPW. The study shows that the stability and reliability of welding process of IFPPW can be guaranteed through the constant energy from the flywheel.Integrated with the advantages of friction pull plug welding,the IFPPW,free from back anvil,is considered as a promising technique in repair of termination keyhole of bobbin tool friction stir welding and point-like defects in aluminum alloy welding.展开更多
Chemical, physical, structural and morphological properties of zinc leaching residue were examined by the combination of various detection means such as AAS, XRF, XRD, M？ssbauer spectrometry, SEM-EDS, TG-DSC, XPS and...Chemical, physical, structural and morphological properties of zinc leaching residue were examined by the combination of various detection means such as AAS, XRF, XRD, M？ssbauer spectrometry, SEM-EDS, TG-DSC, XPS and FTIR. The toxicity characteristic leaching procedure （TCLP） was used to investigate the environmental activity of zinc leaching residue for a short contact time. The phase composition analysis indicated that the zinc leaching residue mainly consists of super refined flocculent particles including zinc ferrite, sulfate and silicate. The physical structural analysis showed that it has a thermal instability and strong water absorption properties. The results of TCLP indicated that the amounts of Zn and Cd in the leaching solution exceed 40 and 90 times of limit, respectively, which demonstrate that this residue is unstable in weak acidic environment for a short contact time.展开更多
Crop yields are affected by climate change and technological advancement.Objectively and quantitatively evaluating the attribution of crop yield change to climate change and technological advancement will ensure susta...Crop yields are affected by climate change and technological advancement.Objectively and quantitatively evaluating the attribution of crop yield change to climate change and technological advancement will ensure sustainable development of agriculture under climate change.In this study,daily climate variables obtained from 553 meteorological stations in China for the period 1961-2010,detailed observations of maize from 653 agricultural meteorological stations for the period 1981-2010,and results using an Agro-Ecological Zones（AEZ） model,are used to explore the attribution of maize（Zea mays L.） yield change to climate change and technological advancement.In the AEZ model,the climatic potential productivity is examined through three step-by-step levels：photosynthetic potential productivity,photosynthetic thermal potential productivity,and climatic potential productivity.The relative impacts of different climate variables on climatic potential productivity of maize from 1961 to 2010 in China are then evaluated.Combined with the observations of maize,the contributions of climate change and technological advancement to maize yield from 1981 to 2010 in China are separated.The results show that,from 1961 to 2010,climate change had a significant adverse impact on the climatic potential productivity of maize in China.Decreased radiation and increased temperature were the main factors leading to the decrease of climatic potential productivity.However,changes in precipitation had only a small effect.The maize yields of the 14 main planting provinces in China increased obviously over the past 30 years,which was opposite to the decreasing trends of climatic potential productivity.This suggests that technological advancement has offset the negative effects of climate change on maize yield.Technological advancement contributed to maize yield increases by 99.6%-141.6%,while climate change contribution was from-41.4%to 0.4%.In particular,the actual maize yields in Shandong,Henan,Jilin,and Inner Mongolia increased by 98.4展开更多
As green tribology is a new field of tribology still in its infancy,understanding its fundamentals is essential for its further development.In this article,a brief historical retrospective on the emergence of green tr...As green tribology is a new field of tribology still in its infancy,understanding its fundamentals is essential for its further development.In this article,a brief historical retrospective on the emergence of green tribology is introduced first,and then the definition,objectives,and disciplinary features of green tribology are clarified.In particular,the technological connotations of green tribology are expounded comprehensively.Also,the developing directions of this new area are envisaged.These findings may contribute to laying the foundation of further advancement in green tribology.展开更多
基金National Social Science Foundation of China(No.06&ZD003)
文摘Using a counterfactual analysis approach, the present paper examines a host of conventional wisdoms relating to issues of farmer, the countryside and agriculture, which are believed to be all originated from the existence of mass surplus laborers in China. When analyzing various sources of statistics, evidence shows that there is no longer a large pool of surplus laborers in rural China as most people believe. Based on this counterfactual result, all related events, such as the direction of agricultural technological changes, the level of comparative productivity of agricultural labor, and the degree of rural-urban income gap must be reconsidered.
基金supported by the National Medium-and Long-Term Program for Science and Technology Development Major Special Funded Projects
文摘The mission objective of Chang’e-3 lunar probe is to achieve our first soft-landing and roving exploration on celestial bodies beyond Earth.On the basis of analyzing technological characteristics in the probe development,key technology breakthroughs and technological promoting roles of Chang’e-3 are both described.
基金Under the auspices of Major Project of National Social Science Foundation of China(No.13&ZD027)National Natural Science Foundation of China(No.41201128,71433008)
文摘Based on patent cooperation data,this study used a range of city network analysis approaches in order to explore the structure of the Chinese city network which is driven by technological knowledge flows.The results revealed the spatial structure,composition structure,hierarchical structure,group structure,and control structure of Chinese city network,as well as its dynamic factors.The major findings are:1) the spatial pattern presents a diamond structure,in which Wuhan is the central city;2) although the invention patent knowledge network is the main part of the broader inter-city innovative cooperation network,it is weaker than the utility model patent;3) as the senior level cities,Beijing,Shanghai and the cities in the Zhujiang(Pearl) River Delta Region show a strong capability of both spreading and controlling technological knowledge;4) whilst a national technology alliance has preliminarily formed,regional alliances have not been adequately established;5) even though the cooperation level amongst weak connection cities is not high,such cities still play an important role in the network as a result of their location within ′structural holes′ in the network;and 6) the major driving forces facilitating inter-city technological cooperation are geographical proximity,hierarchical proximity and technological proximity.
文摘The paper gives an analysis on technical characteristics of repair techniques for friction stir welding defects. To overcome the defects,a new repair technique, inertia friction pull plug welding( IFPPW), was researched and its equipment was developed as well. Elementary datum was achieved by investigating the influences of technological parameters on mechanical properties and by analyzing the structural characteristics of repair joint with IFPPW. The study shows that the stability and reliability of welding process of IFPPW can be guaranteed through the constant energy from the flywheel.Integrated with the advantages of friction pull plug welding,the IFPPW,free from back anvil,is considered as a promising technique in repair of termination keyhole of bobbin tool friction stir welding and point-like defects in aluminum alloy welding.
基金Project(2011AA061001)supported by the Hi-Tech Research and Development Program of ChinaProject(50830301)supported by theKey Program of National Natural Science Foundation of ChinaProject(50925417)supported by the National Science Fund for Distinguished Young Scientists of China
文摘Chemical, physical, structural and morphological properties of zinc leaching residue were examined by the combination of various detection means such as AAS, XRF, XRD, M？ssbauer spectrometry, SEM-EDS, TG-DSC, XPS and FTIR. The toxicity characteristic leaching procedure （TCLP） was used to investigate the environmental activity of zinc leaching residue for a short contact time. The phase composition analysis indicated that the zinc leaching residue mainly consists of super refined flocculent particles including zinc ferrite, sulfate and silicate. The physical structural analysis showed that it has a thermal instability and strong water absorption properties. The results of TCLP indicated that the amounts of Zn and Cd in the leaching solution exceed 40 and 90 times of limit, respectively, which demonstrate that this residue is unstable in weak acidic environment for a short contact time.
基金Supported by the National Natural Science Foundation of China(31371530)China Meteorological Administration Special Public Welfare Research Fund(GYHY201106020)China Meteorological Administration Special Climate Change Research Fund(CCSF201346)
文摘Crop yields are affected by climate change and technological advancement.Objectively and quantitatively evaluating the attribution of crop yield change to climate change and technological advancement will ensure sustainable development of agriculture under climate change.In this study,daily climate variables obtained from 553 meteorological stations in China for the period 1961-2010,detailed observations of maize from 653 agricultural meteorological stations for the period 1981-2010,and results using an Agro-Ecological Zones（AEZ） model,are used to explore the attribution of maize（Zea mays L.） yield change to climate change and technological advancement.In the AEZ model,the climatic potential productivity is examined through three step-by-step levels：photosynthetic potential productivity,photosynthetic thermal potential productivity,and climatic potential productivity.The relative impacts of different climate variables on climatic potential productivity of maize from 1961 to 2010 in China are then evaluated.Combined with the observations of maize,the contributions of climate change and technological advancement to maize yield from 1981 to 2010 in China are separated.The results show that,from 1961 to 2010,climate change had a significant adverse impact on the climatic potential productivity of maize in China.Decreased radiation and increased temperature were the main factors leading to the decrease of climatic potential productivity.However,changes in precipitation had only a small effect.The maize yields of the 14 main planting provinces in China increased obviously over the past 30 years,which was opposite to the decreasing trends of climatic potential productivity.This suggests that technological advancement has offset the negative effects of climate change on maize yield.Technological advancement contributed to maize yield increases by 99.6%-141.6%,while climate change contribution was from-41.4%to 0.4%.In particular,the actual maize yields in Shandong,Henan,Jilin,and Inner Mongolia increased by 98.4
文摘As green tribology is a new field of tribology still in its infancy,understanding its fundamentals is essential for its further development.In this article,a brief historical retrospective on the emergence of green tribology is introduced first,and then the definition,objectives,and disciplinary features of green tribology are clarified.In particular,the technological connotations of green tribology are expounded comprehensively.Also,the developing directions of this new area are envisaged.These findings may contribute to laying the foundation of further advancement in green tribology.
