The action of the composite heat source model in DE-GMAW has been carried out according to the characteristics of the DE-GMA W process, and the distribution of surface and body heat source was analyzed. The weld tempe...The action of the composite heat source model in DE-GMAW has been carried out according to the characteristics of the DE-GMA W process, and the distribution of surface and body heat source was analyzed. The weld temperature field distribution has been derived from the appropriate boundary conditions and the thermal physical property parameters by COMSOL software. The effects of the positions of the surface and body heat source on the cross- sectional shape were investigated by studying the experimental welding thermal cycle curve. The simulated results are fully compliant with the experimental data under the same conditions. This illustrates that the composite heat source model is correct. It reflects the thermal mechanism of DE-GMA W process, and reveals the internal influence of weld shaping.展开更多
Research on carbon cycling has attracted attention from both scientists and policy-makers. Based on material flow analysis, this study systematically budgets the carbon inputs, outputs and balance from 1980 to 2013 fo...Research on carbon cycling has attracted attention from both scientists and policy-makers. Based on material flow analysis, this study systematically budgets the carbon inputs, outputs and balance from 1980 to 2013 for China＇s agro-ecosystem and its sub-systems, including agricultural land use, livestock breeding and rural life. The results show that from 1980 to 2013, both the carbon input and output were growing gradually, with the carbon input doubling from 1.6 Pg C/year in 1980 to 3.4 Pg C/year in 2013, while carbon output grew from 2.2 Pg C/year in 1980 to 3.8 Pg C/year in 2013. From 1980 to 2013, the crop production system in China has remained a carbon source, and the agricultural land uses were also almost all carbon sources instead of carbon sinks. As soil carbon stock plays a very important role in deciding the function of China＇s agro-ecosystem as a carbon sink or source, practices that can promote carbon storage and sequestration will be an essential component of low carbon agriculture development in China.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51165023)
文摘The action of the composite heat source model in DE-GMAW has been carried out according to the characteristics of the DE-GMA W process, and the distribution of surface and body heat source was analyzed. The weld temperature field distribution has been derived from the appropriate boundary conditions and the thermal physical property parameters by COMSOL software. The effects of the positions of the surface and body heat source on the cross- sectional shape were investigated by studying the experimental welding thermal cycle curve. The simulated results are fully compliant with the experimental data under the same conditions. This illustrates that the composite heat source model is correct. It reflects the thermal mechanism of DE-GMA W process, and reveals the internal influence of weld shaping.
基金supported by the National Science & Technology Pillar Program during the 12th Five-year Plan Period (No. 2013BAD11B03)the National Natural Science Foundation of China (Nos. 71573260,71273153,and 71525007)the Basic Scientific Research Fund (No. BSRF201311) for National Nonprofit Institutes from Ministry of Agriculture(MoA),China
文摘Research on carbon cycling has attracted attention from both scientists and policy-makers. Based on material flow analysis, this study systematically budgets the carbon inputs, outputs and balance from 1980 to 2013 for China＇s agro-ecosystem and its sub-systems, including agricultural land use, livestock breeding and rural life. The results show that from 1980 to 2013, both the carbon input and output were growing gradually, with the carbon input doubling from 1.6 Pg C/year in 1980 to 3.4 Pg C/year in 2013, while carbon output grew from 2.2 Pg C/year in 1980 to 3.8 Pg C/year in 2013. From 1980 to 2013, the crop production system in China has remained a carbon source, and the agricultural land uses were also almost all carbon sources instead of carbon sinks. As soil carbon stock plays a very important role in deciding the function of China＇s agro-ecosystem as a carbon sink or source, practices that can promote carbon storage and sequestration will be an essential component of low carbon agriculture development in China.
