Based on cutting principle and technology development of vertical blasthole cutby stage and deck in vertical shaft excavation, combined with the merits of middle spacecharging and toe space charging, the reinforced cu...Based on cutting principle and technology development of vertical blasthole cutby stage and deck in vertical shaft excavation, combined with the merits of middle spacecharging and toe space charging, the reinforced cutting effect of central large-diameterblasthole and the method of cutting blast by stage and deck toe space charging for thevertical large-diameter blastholes was put forward and analyzed theoretically.This new cutblasting method is provided with the advantages of high blasthole using ratio, big cavitybulk, low rate of chunk, even lumpiness, and relatively high energy using ratio.The parameterchoices and practical effects of this cutting method were discussed after in situexperiment.It shows that the decked delay time of 75～100 ms is applicable.展开更多
The time-periodic perturbations of planar Hamiltonian systems are investigated.A necessary condition for the existence of an invariant torus,a sufficient condition for the bifurcation of a unique invariant torus and a...The time-periodic perturbations of planar Hamiltonian systems are investigated.A necessary condition for the existence of an invariant torus,a sufficient condition for the bifurcation of a unique invariant torus and a subharmonic solution are obtained.展开更多
The existence conditions of an invariant torus for general planar periodic perturbed systems are given.It is proved that the perturbed systems may have not only large invariant tori which appear in pair,but also small...The existence conditions of an invariant torus for general planar periodic perturbed systems are given.It is proved that the perturbed systems may have not only large invariant tori which appear in pair,but also small invariant tori.展开更多
In this note we study the existence of a center-focus and a weakly globally positive attractor for the generalized Liénard equations. The results obtained offer a solution to the two problems about pseudolinear s...In this note we study the existence of a center-focus and a weakly globally positive attractor for the generalized Liénard equations. The results obtained offer a solution to the two problems about pseudolinear systems posed by Prof. Roberto Conti.展开更多
As we know, the following nonlinear equation is important in the study of qualitative theory of ordinary differential equations. Some results on the existence have been shown. And we notice that many results on the no...As we know, the following nonlinear equation is important in the study of qualitative theory of ordinary differential equations. Some results on the existence have been shown. And we notice that many results on the nonexistence of limit cycles were obtained by the following theorem.展开更多
Consider a three-dimensional autonomous system of the form of =f(u), u∈R^3, (0.1) where f(0)=0, and Df(0)=. By transforming eq. (0.1) into a normal form equation and then unfolding the truncated equation, one can obt...Consider a three-dimensional autonomous system of the form of =f(u), u∈R^3, (0.1) where f(0)=0, and Df(0)=. By transforming eq. (0.1) into a normal form equation and then unfolding the truncated equation, one can obtain a plane system of the form展开更多
基金Supported by the National Natural Science Foundation of China(50764001)Ministry of Education"Chunhui Program",Guizhou Outstanding Young Talents Foundation(200705)Scientific and Technological Tack-ling Project of Guizhou Province(20073015)
文摘Based on cutting principle and technology development of vertical blasthole cutby stage and deck in vertical shaft excavation, combined with the merits of middle spacecharging and toe space charging, the reinforced cutting effect of central large-diameterblasthole and the method of cutting blast by stage and deck toe space charging for thevertical large-diameter blastholes was put forward and analyzed theoretically.This new cutblasting method is provided with the advantages of high blasthole using ratio, big cavitybulk, low rate of chunk, even lumpiness, and relatively high energy using ratio.The parameterchoices and practical effects of this cutting method were discussed after in situexperiment.It shows that the decked delay time of 75～100 ms is applicable.
基金Progect supported by the National Natural Science Foundation of China.
文摘The time-periodic perturbations of planar Hamiltonian systems are investigated.A necessary condition for the existence of an invariant torus,a sufficient condition for the bifurcation of a unique invariant torus and a subharmonic solution are obtained.
基金Project supported by the National Natural Science Foundation of China.
文摘The existence conditions of an invariant torus for general planar periodic perturbed systems are given.It is proved that the perturbed systems may have not only large invariant tori which appear in pair,but also small invariant tori.
文摘In this note we study the existence of a center-focus and a weakly globally positive attractor for the generalized Liénard equations. The results obtained offer a solution to the two problems about pseudolinear systems posed by Prof. Roberto Conti.
基金Project supported by the National Natural Science Foundation of China
文摘As we know, the following nonlinear equation is important in the study of qualitative theory of ordinary differential equations. Some results on the existence have been shown. And we notice that many results on the nonexistence of limit cycles were obtained by the following theorem.
基金the National Natural Science Foundation of China.
文摘Consider a three-dimensional autonomous system of the form of =f(u), u∈R^3, (0.1) where f(0)=0, and Df(0)=. By transforming eq. (0.1) into a normal form equation and then unfolding the truncated equation, one can obtain a plane system of the form
