The change of stress and temperature in the conform forming process has been studied. On the basis of the law of momentum, the law of momantum moment and the law of energy conservation, the governmental differential e...The change of stress and temperature in the conform forming process has been studied. On the basis of the law of momentum, the law of momantum moment and the law of energy conservation, the governmental differential equations of stress and temperature in the conform metal forming process have been derived, whose definite conditions are given by material mechanics, elastic machanics and plastic mechanics. The analytic solution of these equations has been successfully obtained and as a result, the solid foundations and scientific guide for the further development of this prospective metal processing techique have been established.展开更多
in this paper, taking enterprise vitality as a target, an evaluation method of the economic development state of enterprise is proposed by using differential model. The solution of the differential model is discussed....in this paper, taking enterprise vitality as a target, an evaluation method of the economic development state of enterprise is proposed by using differential model. The solution of the differential model is discussed. The direct fitting methods and operational formulas for the parameters in the differenticl model are given. The feasible conditions of the methods are shown. It is an advantage that the methods have gotten rid of discretization error in contrast with the methods of grey theory.展开更多
Discuss a class of real planar cubic systems with a critical point O (0,0) of nine orders and obtain the conditions for its limit cycle surrounding the origin, and prove that when small pertubations of coefficients ar...Discuss a class of real planar cubic systems with a critical point O (0,0) of nine orders and obtain the conditions for its limit cycle surrounding the origin, and prove that when small pertubations of coefficients are made, the critical point O (0,0) of nine orders is split into nine real simple critical points and the limit cycle surrounding the origin becomes the limit cycle containing nine critical points in its interior.展开更多
文摘The change of stress and temperature in the conform forming process has been studied. On the basis of the law of momentum, the law of momantum moment and the law of energy conservation, the governmental differential equations of stress and temperature in the conform metal forming process have been derived, whose definite conditions are given by material mechanics, elastic machanics and plastic mechanics. The analytic solution of these equations has been successfully obtained and as a result, the solid foundations and scientific guide for the further development of this prospective metal processing techique have been established.
文摘in this paper, taking enterprise vitality as a target, an evaluation method of the economic development state of enterprise is proposed by using differential model. The solution of the differential model is discussed. The direct fitting methods and operational formulas for the parameters in the differenticl model are given. The feasible conditions of the methods are shown. It is an advantage that the methods have gotten rid of discretization error in contrast with the methods of grey theory.
基金The Natural Science Foundation of Hunan Province !(No .97JJN 70 )
文摘Discuss a class of real planar cubic systems with a critical point O (0,0) of nine orders and obtain the conditions for its limit cycle surrounding the origin, and prove that when small pertubations of coefficients are made, the critical point O (0,0) of nine orders is split into nine real simple critical points and the limit cycle surrounding the origin becomes the limit cycle containing nine critical points in its interior.
