To obtain the phase transformation latent heat corresponding to different cooling rates with low test workload and cost,the Newton thermal analysis method and the improved Newtonian thermal analysis method were discus...To obtain the phase transformation latent heat corresponding to different cooling rates with low test workload and cost,the Newton thermal analysis method and the improved Newtonian thermal analysis method were discussed based on the cooling curve obtained in the end-quench test.The validity of two methods was given by the latent heat calculation of 45^(#) steel.The results show that the relative error of latent heat is 5.20%through the improved Newtonian thermal analysis method,which is more accurate than the Newtonian thermal analysis method.Furthermore,the latent heat release of phase transformation of the self-designed CSU-A1 powder metallurgy nickel-based superalloy increases from 4.3 to 12.29 J/g when the cooling rate decreases from 50.15 to 33.40℃/min,because there is more sufficient time for the alloy microstructure to complete the phase transformation process when the cooling rate is smaller.展开更多
The 1-year（2009-2010） measurements are analyzed of the urban surface energy balance（SEB） obtained from the sensors located at three vertical layers of a 325-m tower in downtown Beijing.Results show that：（1） The...The 1-year（2009-2010） measurements are analyzed of the urban surface energy balance（SEB） obtained from the sensors located at three vertical layers of a 325-m tower in downtown Beijing.Results show that：（1） The measurements from the 325-m tower represent the SEB characteristics of the cities located in semi-humid warm-temperate continental monsoon climate zone.In a typical hot and rainy summer,cold and dry winter,the measured Bowen ratio is minimum in summer and maximum in winter.The Bowen ratio measured at 140 m for spring,summer,autumn,and winter are 2.86,0.82,1.17,and 4.16 respectively.（2） At the height of 140-m（in the constant flux layer）,the noontime albedo is ~0.10 for summer,~0.12 for spring and autumn,and ~0.14 for winter.The ratios of daytime sensible heat flux,latent heat flux,and storage heat flux to net radiation are 0.25,0.16,and 0.59 for clear-sky days,and 0.33,0.19,and 0.48 for cloudy days respectively.（3） Under clear-sky days,the nighttime sensible heat flux is almost zero,but the latent heat flux is greater than zero.For cloudy days,the nighttime sensible heat flux is slightly greater than the latent heat flux in winter.The nighttime upward heat flux is presumably due to the anthropogenic release（mainly latent heat for summer,while latent and sensible heat for winter）.展开更多
基金the financial supports from the National Key Research and Development Program of China(No.2016YFB0700300)the Postgraduate Independent Exploration and Innovation Project of Central South University,China(No.2019zzts262)。
文摘To obtain the phase transformation latent heat corresponding to different cooling rates with low test workload and cost,the Newton thermal analysis method and the improved Newtonian thermal analysis method were discussed based on the cooling curve obtained in the end-quench test.The validity of two methods was given by the latent heat calculation of 45^(#) steel.The results show that the relative error of latent heat is 5.20%through the improved Newtonian thermal analysis method,which is more accurate than the Newtonian thermal analysis method.Furthermore,the latent heat release of phase transformation of the self-designed CSU-A1 powder metallurgy nickel-based superalloy increases from 4.3 to 12.29 J/g when the cooling rate decreases from 50.15 to 33.40℃/min,because there is more sufficient time for the alloy microstructure to complete the phase transformation process when the cooling rate is smaller.
基金supported by National Natural Science Foundation of China (Grant No. 41175015)the Ministry of Science and Technology of China (Grant Nos. GYHY200906026,GYHY201106050,2008BAC37B04,and 2006BAJ02A01)
文摘The 1-year（2009-2010） measurements are analyzed of the urban surface energy balance（SEB） obtained from the sensors located at three vertical layers of a 325-m tower in downtown Beijing.Results show that：（1） The measurements from the 325-m tower represent the SEB characteristics of the cities located in semi-humid warm-temperate continental monsoon climate zone.In a typical hot and rainy summer,cold and dry winter,the measured Bowen ratio is minimum in summer and maximum in winter.The Bowen ratio measured at 140 m for spring,summer,autumn,and winter are 2.86,0.82,1.17,and 4.16 respectively.（2） At the height of 140-m（in the constant flux layer）,the noontime albedo is ~0.10 for summer,~0.12 for spring and autumn,and ~0.14 for winter.The ratios of daytime sensible heat flux,latent heat flux,and storage heat flux to net radiation are 0.25,0.16,and 0.59 for clear-sky days,and 0.33,0.19,and 0.48 for cloudy days respectively.（3） Under clear-sky days,the nighttime sensible heat flux is almost zero,but the latent heat flux is greater than zero.For cloudy days,the nighttime sensible heat flux is slightly greater than the latent heat flux in winter.The nighttime upward heat flux is presumably due to the anthropogenic release（mainly latent heat for summer,while latent and sensible heat for winter）.
