Social stock for metal determines secondary or recoverable resources to a certain extent.Top-down analysis method for the studying of metal in social stock was given.Influences of metal consumption under three circums...Social stock for metal determines secondary or recoverable resources to a certain extent.Top-down analysis method for the studying of metal in social stock was given.Influences of metal consumption under three circumstances,that is keeping constant,varying in a linear trend and in an exponential trend,on one kind of metal’s social stock,recyclable ratio and average age were analyzed.Al-contents and Cu-contents in social stock for China during the period 2006-2009 were calculated.The results reveal that Al-contents and Cu-contents in social stock kept increasing and reached 88.9 million tons and 51.4 millions tons in 2009,respectively,their average recyclable ratios are 1.45% and 0.30%,and the average ages are 4.65 years and 6.89 years,respectively.The recyclable ratios and average ages of Al-contents and Cu-contents in social stock will rise in future along with the decline of the increasing rate of aluminum consumption and copper consumption.展开更多
本文先给出整式方程诸根任意幂之和的递推公式,然后举例说明其应用。命题设x<sub>i</sub>（i=1,2,3,…,n）是方程x<sup>n</sup>+a<sub>1</sub>x<sup>n-1</sup>+a<sub>2</sub&...本文先给出整式方程诸根任意幂之和的递推公式,然后举例说明其应用。命题设x<sub>i</sub>（i=1,2,3,…,n）是方程x<sup>n</sup>+a<sub>1</sub>x<sup>n-1</sup>+a<sub>2</sub>x<sup>n-2</sup>+…+a<sub>n</sub>=0（a<sub>n</sub>≠0）的n个根,记S<sub>k</sub>=sum from i=1 to n x<sub>i</sub><sup>k</sup>。展开更多
基金Project (71003018) supported by the National Natural Science Foundation of ChinaProject (N110402003) supported by the Fundamental Research Funds for the Central Universities,China
文摘Social stock for metal determines secondary or recoverable resources to a certain extent.Top-down analysis method for the studying of metal in social stock was given.Influences of metal consumption under three circumstances,that is keeping constant,varying in a linear trend and in an exponential trend,on one kind of metal’s social stock,recyclable ratio and average age were analyzed.Al-contents and Cu-contents in social stock for China during the period 2006-2009 were calculated.The results reveal that Al-contents and Cu-contents in social stock kept increasing and reached 88.9 million tons and 51.4 millions tons in 2009,respectively,their average recyclable ratios are 1.45% and 0.30%,and the average ages are 4.65 years and 6.89 years,respectively.The recyclable ratios and average ages of Al-contents and Cu-contents in social stock will rise in future along with the decline of the increasing rate of aluminum consumption and copper consumption.
文摘本文先给出整式方程诸根任意幂之和的递推公式,然后举例说明其应用。命题设x<sub>i</sub>（i=1,2,3,…,n）是方程x<sup>n</sup>+a<sub>1</sub>x<sup>n-1</sup>+a<sub>2</sub>x<sup>n-2</sup>+…+a<sub>n</sub>=0（a<sub>n</sub>≠0）的n个根,记S<sub>k</sub>=sum from i=1 to n x<sub>i</sub><sup>k</sup>。
