The design of tubular steel scaffold-type shoring is usually performed by calculating the load capacity of the elements, taking into account their axial strength, mainly. Geometric stiffness effects and changes in the...The design of tubular steel scaffold-type shoring is usually performed by calculating the load capacity of the elements, taking into account their axial strength, mainly. Geometric stiffness effects and changes in the stiffness of connections are seldom considered. This paper assesses the stability of tubular steel shores using experimental and numerical approaches that take into account geometric nonlinearities as well as the features of the elements used to make the link between the steel tubes （pressed double coupler--right angle）. The increase in overall stiffness generated by diagonal bars used in the analyzed models was examined. The results obtained show the importance of using P-delta analyses in this kind of structure in order to evaluate structure＇s overall stability even when compressive stresses are within acceptable ranges of code limits.展开更多
This paper considers the global existence and nonexistence of positive solutions for the following volterra integral equations wbers Matrix B is called a positive definite one, if all the principal minors have positi...This paper considers the global existence and nonexistence of positive solutions for the following volterra integral equations wbers Matrix B is called a positive definite one, if all the principal minors have positive detechants. By considering the existence of positivve solutions for algebra equations, it is proved that if I-A is a positive definite matrix,where I is an identity matrix, then (I) bas global positive solution 1 Otherwise, (I)has no continous nbndeereasing positive solution.展开更多
A improving Steady State Genetic Algorithm for global optimization over linear constraint non-convex programming problem is presented. By convex analyzing, the primal optimal problem can be converted to an equivalent ...A improving Steady State Genetic Algorithm for global optimization over linear constraint non-convex programming problem is presented. By convex analyzing, the primal optimal problem can be converted to an equivalent problem, in which only the information of convex extremes of feasible space is included, and is more easy for GAs to solve. For avoiding invalid genetic operators, a redesigned convex crossover operator is also performed in evolving. As a integrality, the quality of two problem is proven, and a method is also given to get all extremes in linear constraint space. Simulation result show that new algorithm not only converges faster, but also can maintain an diversity population, and can get the global optimum of test problem.展开更多
The initial boundary value problem for the fourth-order wave equation u_(tt)+△~2u+u=|u|^(p-1)u is considered.The existence and uniqueness of global weak solutions is obtained by using the Galerkin method and the conc...The initial boundary value problem for the fourth-order wave equation u_(tt)+△~2u+u=|u|^(p-1)u is considered.The existence and uniqueness of global weak solutions is obtained by using the Galerkin method and the concept of stable set due to Sattinger.展开更多
Aneuploidy is commonly observed in breast cancer and is associated with poor prognosis. One frequent type of aneuploidy, hypertetraploidy, may derive from ploidy duplication of hyperdiploid cells. However, the patholo...Aneuploidy is commonly observed in breast cancer and is associated with poor prognosis. One frequent type of aneuploidy, hypertetraploidy, may derive from ploidy duplication of hyperdiploid cells. However, the pathological consequences of ploidy duplication in breast cancer progression have not been characterized. Here, we present an experimental system demonstrating spontaneous appearance of hypertetraploid cells from organ-specific metastatic variants of the MDA-MB-231 breast cancer cell line through ploidy duplication in vitro and in vivo. The hypertetraploid progenies showed increased metastatic potential to lung and brain, but not to bone, which may be partially explained by the distinct capillary structures in these organs that confer differential lodging advantages to tumor cells with enlarged size. Our results suggest a potential mechanistic link between ploidy duplication and enhancement of metastatic potentials, as was observed in previous clinical studies of breast cancer.展开更多
This paper is concerned with a dissipative nonlinear Schroedinger equation with a harmonic potential. By using some intricate inequalities and the argument of priori estimates, some behaviors of the solution are inves...This paper is concerned with a dissipative nonlinear Schroedinger equation with a harmonic potential. By using some intricate inequalities and the argument of priori estimates, some behaviors of the solution are investigated.展开更多
In this paper, we consider a nonautonomous competitive model with dispersion and a finite number of discrete delays. The system, which consists of two Lotka-Volterra patches, has two competitors: one can disperse betw...In this paper, we consider a nonautonomous competitive model with dispersion and a finite number of discrete delays. The system, which consists of two Lotka-Volterra patches, has two competitors: one can disperse between the two patches, but the other is confined to one patch and cannot disperse. Our purpose is to demonstrate that the dispersion rates have no effect on the uniform persistence of the solutions of the system. Furthermore, we establish the conditions under which the system admits a positive periodic solution which attracts all solutions.展开更多
文摘The design of tubular steel scaffold-type shoring is usually performed by calculating the load capacity of the elements, taking into account their axial strength, mainly. Geometric stiffness effects and changes in the stiffness of connections are seldom considered. This paper assesses the stability of tubular steel shores using experimental and numerical approaches that take into account geometric nonlinearities as well as the features of the elements used to make the link between the steel tubes （pressed double coupler--right angle）. The increase in overall stiffness generated by diagonal bars used in the analyzed models was examined. The results obtained show the importance of using P-delta analyses in this kind of structure in order to evaluate structure＇s overall stability even when compressive stresses are within acceptable ranges of code limits.
文摘This paper considers the global existence and nonexistence of positive solutions for the following volterra integral equations wbers Matrix B is called a positive definite one, if all the principal minors have positive detechants. By considering the existence of positivve solutions for algebra equations, it is proved that if I-A is a positive definite matrix,where I is an identity matrix, then (I) bas global positive solution 1 Otherwise, (I)has no continous nbndeereasing positive solution.
文摘A improving Steady State Genetic Algorithm for global optimization over linear constraint non-convex programming problem is presented. By convex analyzing, the primal optimal problem can be converted to an equivalent problem, in which only the information of convex extremes of feasible space is included, and is more easy for GAs to solve. For avoiding invalid genetic operators, a redesigned convex crossover operator is also performed in evolving. As a integrality, the quality of two problem is proven, and a method is also given to get all extremes in linear constraint space. Simulation result show that new algorithm not only converges faster, but also can maintain an diversity population, and can get the global optimum of test problem.
基金the National Natural Science Foundation of China(10301026)the Research Foundation of Chengdu University of Information Technology(CRF200702)
文摘The initial boundary value problem for the fourth-order wave equation u_(tt)+△~2u+u=|u|^(p-1)u is considered.The existence and uniqueness of global weak solutions is obtained by using the Galerkin method and the concept of stable set due to Sattinger.
文摘Aneuploidy is commonly observed in breast cancer and is associated with poor prognosis. One frequent type of aneuploidy, hypertetraploidy, may derive from ploidy duplication of hyperdiploid cells. However, the pathological consequences of ploidy duplication in breast cancer progression have not been characterized. Here, we present an experimental system demonstrating spontaneous appearance of hypertetraploid cells from organ-specific metastatic variants of the MDA-MB-231 breast cancer cell line through ploidy duplication in vitro and in vivo. The hypertetraploid progenies showed increased metastatic potential to lung and brain, but not to bone, which may be partially explained by the distinct capillary structures in these organs that confer differential lodging advantages to tumor cells with enlarged size. Our results suggest a potential mechanistic link between ploidy duplication and enhancement of metastatic potentials, as was observed in previous clinical studies of breast cancer.
基金the Scientific Research Fund of Sichuan Provincial Education Department (2006A063).
文摘This paper is concerned with a dissipative nonlinear Schroedinger equation with a harmonic potential. By using some intricate inequalities and the argument of priori estimates, some behaviors of the solution are investigated.
基金This research is supported by the National Natural Science Foundation of China the Natural Science Foundation of Henan Province.
文摘In this paper, we consider a nonautonomous competitive model with dispersion and a finite number of discrete delays. The system, which consists of two Lotka-Volterra patches, has two competitors: one can disperse between the two patches, but the other is confined to one patch and cannot disperse. Our purpose is to demonstrate that the dispersion rates have no effect on the uniform persistence of the solutions of the system. Furthermore, we establish the conditions under which the system admits a positive periodic solution which attracts all solutions.
