In this paper,we prove the symmetry of the solution to overdetermined problem for the equationσ_(k)(D^(2)u-ul)=C^(k)_(n)in hyperbolic space.Our approach is based on establishing a Rellich-Pohozaev type identity and u...In this paper,we prove the symmetry of the solution to overdetermined problem for the equationσ_(k)(D^(2)u-ul)=C^(k)_(n)in hyperbolic space.Our approach is based on establishing a Rellich-Pohozaev type identity and using a P function.Our result generalizes the overdetermined problem for Hessian equation in Euclidean space.展开更多
This paper considers overdetermined boundary problems.Firstly,the author gives a proof of the Payne-Schaefer conjecture about an overdetermined problem of sixth order in the two-dimensional case and under an additiona...This paper considers overdetermined boundary problems.Firstly,the author gives a proof of the Payne-Schaefer conjecture about an overdetermined problem of sixth order in the two-dimensional case and under an additional condition for the case of dimension no less than three.Secondly,the author proves an integral identity for an overdetermined problem of fourth order which can be used to deduce Bennett's symmetry theorem.Finally,the author proves a symmetry result for an overdetermined problem of second order by integral identities.展开更多
The working platforms supported with multiple extensible legs must be leveled before they come into operation.Although the supporting stiffness and reliability of the platform are improved with the increasing number o...The working platforms supported with multiple extensible legs must be leveled before they come into operation.Although the supporting stiffness and reliability of the platform are improved with the increasing number of the supporting legs,the increased overdetermination of the multi-leg platform systems leads to leveling coupling problem among legs and virtual leg problem in which some of the supporting legs bear zero or quasi zero loads.These problems make it quite complex and time consuming to level such a multi-leg platform.Based on rigid body kinematics,an approximate equation is formulated to rapidly calculate the leg extension for leveling a rigid platform,then a proportional speed control strategy is proposed to reduce the unexpected platform distortion and leveling coupling between supporting legs.Taking both the load coupling between supporting legs and the elastic flexibility of the working platform into consideration,an optimal balancing legs’ loads(OBLL) model is firstly put forward to deal with the traditional virtual leg problem.By taking advantage of the concept of supporting stiffness matrix,a coupling extension method(CEM) is developed to solve this OBLL problem for multi-leg flexible platform.At the end,with the concept of supporting stiffness matrix and static transmissibility matrix,an optimal load balancing leveling method is proposed to achieve geometric leveling and legs’ loads balancing simultaneously.Three numerical examples are given out to illustrate the performance of proposed methods.This paper proposes a method which can effectively quantify all of the legs’ extension at the same time,achieve geometric leveling and legs’ loads balancing simultaneously.By using the proposed methods,the stability,precision and efficiency of auto-leveling control process can be improved.展开更多
基金The research is supported by the National Science Foundation of China(No.11721101)the National Key R and D Program of China 2020YFA0713100.
文摘In this paper,we prove the symmetry of the solution to overdetermined problem for the equationσ_(k)(D^(2)u-ul)=C^(k)_(n)in hyperbolic space.Our approach is based on establishing a Rellich-Pohozaev type identity and using a P function.Our result generalizes the overdetermined problem for Hessian equation in Euclidean space.
文摘This paper considers overdetermined boundary problems.Firstly,the author gives a proof of the Payne-Schaefer conjecture about an overdetermined problem of sixth order in the two-dimensional case and under an additional condition for the case of dimension no less than three.Secondly,the author proves an integral identity for an overdetermined problem of fourth order which can be used to deduce Bennett's symmetry theorem.Finally,the author proves a symmetry result for an overdetermined problem of second order by integral identities.
基金supported by Shandong Provincial Natural Science Foundation of China(Grant No.ZR2010EL003)
文摘The working platforms supported with multiple extensible legs must be leveled before they come into operation.Although the supporting stiffness and reliability of the platform are improved with the increasing number of the supporting legs,the increased overdetermination of the multi-leg platform systems leads to leveling coupling problem among legs and virtual leg problem in which some of the supporting legs bear zero or quasi zero loads.These problems make it quite complex and time consuming to level such a multi-leg platform.Based on rigid body kinematics,an approximate equation is formulated to rapidly calculate the leg extension for leveling a rigid platform,then a proportional speed control strategy is proposed to reduce the unexpected platform distortion and leveling coupling between supporting legs.Taking both the load coupling between supporting legs and the elastic flexibility of the working platform into consideration,an optimal balancing legs’ loads(OBLL) model is firstly put forward to deal with the traditional virtual leg problem.By taking advantage of the concept of supporting stiffness matrix,a coupling extension method(CEM) is developed to solve this OBLL problem for multi-leg flexible platform.At the end,with the concept of supporting stiffness matrix and static transmissibility matrix,an optimal load balancing leveling method is proposed to achieve geometric leveling and legs’ loads balancing simultaneously.Three numerical examples are given out to illustrate the performance of proposed methods.This paper proposes a method which can effectively quantify all of the legs’ extension at the same time,achieve geometric leveling and legs’ loads balancing simultaneously.By using the proposed methods,the stability,precision and efficiency of auto-leveling control process can be improved.
