Let M^n be an n-dimensional complete noncompact oriented weakly stable constant mean curvature hypersurface in an （n ＋ 1）-dimensional Riemannian manifold N^n＋1 whose （n - 1）th Ricci curvature satisfying Ric^N（...Let M^n be an n-dimensional complete noncompact oriented weakly stable constant mean curvature hypersurface in an （n ＋ 1）-dimensional Riemannian manifold N^n＋1 whose （n - 1）th Ricci curvature satisfying Ric^N（n-1） （n - 1）c. Denote by H and φ the mean curvature and the trace-free second fundamental form of M respectively. If ｜φ｜^2 - （n- 2）√n（n- 1）｜H｜｜φ｜＋ n（2n - 1）（H^2＋ c） 〉 0, then M does not admit nonconstant bounded harmonic functions with finite Dirichlet integral. In particular, if N has bounded geometry and c ＋ H^2 〉 0, then M must have only one end.展开更多
In order to overcome the shortcomings of the traditional sling suspension method,such as complex structure of suspension truss,large running resistance,and low precision of position servo system,a gravity compensation...In order to overcome the shortcomings of the traditional sling suspension method,such as complex structure of suspension truss,large running resistance,and low precision of position servo system,a gravity compensation method of lunar rover based on the combination of active suspension and active position following of magnetic levitation is proposed,and the overall design is carried out.The dynamic model of the suspension module of microgravity compensation system was established,and the decoupling control between the constant force component and the position servo component was analyzed and verified.The constant tension control was achieved by using hybrid force/position control.The position following control was realized by using fuzzy adaptive PID(proportional⁃integral⁃differential)control.The stable suspension control was realized based on the principle of force balance.The simulation results show that the compensation accuracy of constant tension could reach more than 95%,the position deviation was less than 5 mm,the position deviation angle was less than 0.025°,and the air gap recovered stability within 0.1 s.The gravity compensation system has excellent dynamic performance and can meet the requirements of microgravity simulation experiment of lunar rover.展开更多
The cadmium(Ⅱ)glycinamide system was modeled and its stability constants were calculated by a unified mathematical treatment for experimental data obtained from ion selective electrode (ISE) and differential pulse po...The cadmium(Ⅱ)glycinamide system was modeled and its stability constants were calculated by a unified mathematical treatment for experimental data obtained from ion selective electrode (ISE) and differential pulse polarography (DPP). It has been shown that very much the same experimental complex formation curve (ECFC) and theoretical complex formation curve (TCFC) could be given from both experimental techniques for the same experimental conditions, such as the same total ligand c(LT) and metal ion c(MT) concentrations. The combination of the two techniques is of many advantages as ISE can be performed at low a c(LT):c(MT) ratio and significantly higher c(MT), whereas DPP could be used well at larger the c(LT):c(MT) ratio and very low c(MT). This makes it possible to study a metal-ligand system in much broader range of experimental conditions that, in turn, provides us more data and information about the metal-ligand system of interest. Application of the unified mathematical treatment to the cadmium-glycinamide system in this paper, three new complexes MHL, ML3 and ML3(OH) as well as two complexes ML and ML2, reported in literatures, could be modeled and all their stability constants have been refined.展开更多
基金Supported by the National Natural Science Foundation of China (10771187 10671087)+1 种基金Trans-Century Training Programme Foundation for Talents by the Ministry of Education of ChinaJiangxi Province Natural Science Foundation (2008GZS0060)
文摘Let M^n be an n-dimensional complete noncompact oriented weakly stable constant mean curvature hypersurface in an （n ＋ 1）-dimensional Riemannian manifold N^n＋1 whose （n - 1）th Ricci curvature satisfying Ric^N（n-1） （n - 1）c. Denote by H and φ the mean curvature and the trace-free second fundamental form of M respectively. If ｜φ｜^2 - （n- 2）√n（n- 1）｜H｜｜φ｜＋ n（2n - 1）（H^2＋ c） 〉 0, then M does not admit nonconstant bounded harmonic functions with finite Dirichlet integral. In particular, if N has bounded geometry and c ＋ H^2 〉 0, then M must have only one end.
基金the National Natural Science Foundation of China(Grant Nos.51305384 and 52075466)。
文摘In order to overcome the shortcomings of the traditional sling suspension method,such as complex structure of suspension truss,large running resistance,and low precision of position servo system,a gravity compensation method of lunar rover based on the combination of active suspension and active position following of magnetic levitation is proposed,and the overall design is carried out.The dynamic model of the suspension module of microgravity compensation system was established,and the decoupling control between the constant force component and the position servo component was analyzed and verified.The constant tension control was achieved by using hybrid force/position control.The position following control was realized by using fuzzy adaptive PID(proportional⁃integral⁃differential)control.The stable suspension control was realized based on the principle of force balance.The simulation results show that the compensation accuracy of constant tension could reach more than 95%,the position deviation was less than 5 mm,the position deviation angle was less than 0.025°,and the air gap recovered stability within 0.1 s.The gravity compensation system has excellent dynamic performance and can meet the requirements of microgravity simulation experiment of lunar rover.
文摘The cadmium(Ⅱ)glycinamide system was modeled and its stability constants were calculated by a unified mathematical treatment for experimental data obtained from ion selective electrode (ISE) and differential pulse polarography (DPP). It has been shown that very much the same experimental complex formation curve (ECFC) and theoretical complex formation curve (TCFC) could be given from both experimental techniques for the same experimental conditions, such as the same total ligand c(LT) and metal ion c(MT) concentrations. The combination of the two techniques is of many advantages as ISE can be performed at low a c(LT):c(MT) ratio and significantly higher c(MT), whereas DPP could be used well at larger the c(LT):c(MT) ratio and very low c(MT). This makes it possible to study a metal-ligand system in much broader range of experimental conditions that, in turn, provides us more data and information about the metal-ligand system of interest. Application of the unified mathematical treatment to the cadmium-glycinamide system in this paper, three new complexes MHL, ML3 and ML3(OH) as well as two complexes ML and ML2, reported in literatures, could be modeled and all their stability constants have been refined.
