Semi-inverse method, which is an integration and an extension of Hu's try-and-error method, Chien's veighted residual method and Liu's systematic method, is proposed to establish generalized variational pr...Semi-inverse method, which is an integration and an extension of Hu's try-and-error method, Chien's veighted residual method and Liu's systematic method, is proposed to establish generalized variational principles with multi-variables without arty variational crisis phenomenon. The method is to construct an energy trial-functional with an unknown function F, which can be readily identified by making the trial-functional stationary and using known constraint equations. As a result generalized variational principles with two kinds of independent variables (such as well-known Hellinger-Reissner variational principle and Hu-Washizu principle) and generalized variational principles with three kinds of independent variables (such as Chien's generalized variational principles) in elasticity have been deduced without using Lagrange multiplier method. By semi-inverse method, the author has also proved that Hu-Washizu principle is actually a variational principle with only two kinds of independent variables, stress-strain relations are still its constraints.展开更多
China's energy consumption for agricultural production has relied on petroleum and coal with relatively low input from power and other types of energy for a long time.Projections indicate that as China's exist...China's energy consumption for agricultural production has relied on petroleum and coal with relatively low input from power and other types of energy for a long time.Projections indicate that as China's existing development trend leads to substantial growth of energy demand for agricultural production,such a long term irrational energy consumption pattern would unlikely be able to meet the needs of the country's developing agricultural sector.As such,it is recommended that China's agricultural sector should follow the national energy development strategy guideline by gradually increasing the use of wind power,solar energy,biomass and other new energy sources while advancing technological innovations on traditional energy sources.Meanwhile,as the consumption structure of three major energy sources(i.e.petroleum,coal,and power)is optimized,development and application of biomass from agriculture as raw materials for alternative energy should be enhanced.Lastly,the development and application of wind power,solar energy,and hydropower in agricultural production should be increased in areas where appropriate.展开更多
文摘Semi-inverse method, which is an integration and an extension of Hu's try-and-error method, Chien's veighted residual method and Liu's systematic method, is proposed to establish generalized variational principles with multi-variables without arty variational crisis phenomenon. The method is to construct an energy trial-functional with an unknown function F, which can be readily identified by making the trial-functional stationary and using known constraint equations. As a result generalized variational principles with two kinds of independent variables (such as well-known Hellinger-Reissner variational principle and Hu-Washizu principle) and generalized variational principles with three kinds of independent variables (such as Chien's generalized variational principles) in elasticity have been deduced without using Lagrange multiplier method. By semi-inverse method, the author has also proved that Hu-Washizu principle is actually a variational principle with only two kinds of independent variables, stress-strain relations are still its constraints.
基金Supported by the Special Funds for Basic Scientific Research of China s National Nonprofit Research Institutions(2008YWF3-06)
文摘China's energy consumption for agricultural production has relied on petroleum and coal with relatively low input from power and other types of energy for a long time.Projections indicate that as China's existing development trend leads to substantial growth of energy demand for agricultural production,such a long term irrational energy consumption pattern would unlikely be able to meet the needs of the country's developing agricultural sector.As such,it is recommended that China's agricultural sector should follow the national energy development strategy guideline by gradually increasing the use of wind power,solar energy,biomass and other new energy sources while advancing technological innovations on traditional energy sources.Meanwhile,as the consumption structure of three major energy sources(i.e.petroleum,coal,and power)is optimized,development and application of biomass from agriculture as raw materials for alternative energy should be enhanced.Lastly,the development and application of wind power,solar energy,and hydropower in agricultural production should be increased in areas where appropriate.
