An optimal midcourse trajectory planning approach that considers the capture region（CR） of the terminal guidance is proposed in this article based on the Gauss pseudospectral method（GPM）. Firstly, the planar CR of...An optimal midcourse trajectory planning approach that considers the capture region（CR） of the terminal guidance is proposed in this article based on the Gauss pseudospectral method（GPM）. Firstly, the planar CR of the proportional navigation in terminal guidance is analyzed and innovatively introduced in the midcourse trajectory planning problems, with the collision triangle（CT） serving as the ideal terminal states parameters of the midcourse phase, and the CR area serving as the robustness against target maneuvers. Secondly, the midcourse trajectory planning problem that considers the path, terminal and control constraints is formulated and the well-developed GPM is used to generate the nominal trajectory that meets the CR demands. The interceptor will reshape the trajectory only when the former CR fails to cover the target, which has loosened the critical demand for frequent trajectory modification. Finally, the simulations of four different scenarios are carried out and the results prove the effectiveness and optimality of the proposed method.展开更多
Delegation mechanism in Internet of Things(IoT)allows users to share some of their permissions with others.Cloud-based delegation solutions require that only the user who has registered in the cloud can be delegated p...Delegation mechanism in Internet of Things(IoT)allows users to share some of their permissions with others.Cloud-based delegation solutions require that only the user who has registered in the cloud can be delegated permissions.It is not convenient when a permission is delegated to a large number of temporarily users.Therefore,some works like CapBAC delegate permissions locally in an offline way.However,this is difficult to revoke and modify the offline delegated permissions.In this work,we propose a traceable capability-based access control approach(TCAC)that can revoke and modify permissions by tracking the trajectories of permissions delegation.We define a time capability tree(TCT)that can automatically extract permissions trajectories,and we also design a new capability token to improve the permission verification,revocation and modification efficiency.The experiment results show that TCAC has less token verification and revocation/modification time than those of CapBAC and xDBAuth.TCAC can discover 73.3%unvisited users in the case of delegating and accessing randomly.This provides more information about the permissions delegation relationships,and opens up new possibilities to guarantee the global security in IoT delegation system.To the best of our knowledge,TCAC is the first work to capture the unvisited permissions.展开更多
The hypersonic interception in near space is a great challenge because of the target’s unpredictable trajectory, which demands the interceptors of trajectory cluster coverage of the predicted area and optimal traject...The hypersonic interception in near space is a great challenge because of the target’s unpredictable trajectory, which demands the interceptors of trajectory cluster coverage of the predicted area and optimal trajectory modification capability aiming at the consistently updating predicted impact point(PIP) in the midcourse phase. A novel midcourse optimal trajectory cluster generation and trajectory modification algorithm is proposed based on the neighboring optimal control theory. Firstly, the midcourse trajectory optimization problem is introduced; the necessary conditions for the optimal control and the transversality constraints are given.Secondly, with the description of the neighboring optimal trajectory existence theory(NOTET), the neighboring optimal control(NOC)algorithm is derived by taking the second order partial derivations with the necessary conditions and transversality conditions. The revised terminal constraints are reversely integrated to the initial time and the perturbations of the co-states are further expressed with the states deviations and terminal constraints modifications.Thirdly, the simulations of two different scenarios are carried out and the results prove the effectiveness and optimality of the proposed method.展开更多
基金supported by the National Natural Science Foundation of China(6157337461503408)
文摘An optimal midcourse trajectory planning approach that considers the capture region（CR） of the terminal guidance is proposed in this article based on the Gauss pseudospectral method（GPM）. Firstly, the planar CR of the proportional navigation in terminal guidance is analyzed and innovatively introduced in the midcourse trajectory planning problems, with the collision triangle（CT） serving as the ideal terminal states parameters of the midcourse phase, and the CR area serving as the robustness against target maneuvers. Secondly, the midcourse trajectory planning problem that considers the path, terminal and control constraints is formulated and the well-developed GPM is used to generate the nominal trajectory that meets the CR demands. The interceptor will reshape the trajectory only when the former CR fails to cover the target, which has loosened the critical demand for frequent trajectory modification. Finally, the simulations of four different scenarios are carried out and the results prove the effectiveness and optimality of the proposed method.
基金This work supports in part by National Key R&D Program of China(No.2018YFB2100400)National Science Foundation of China(No.61872100)+1 种基金Industrial Internet Innovation and Development Project of China(2019)State Grid Corporation of China Co.,Ltd.technology project(No.5700-202019187A-0-0-00).
文摘Delegation mechanism in Internet of Things(IoT)allows users to share some of their permissions with others.Cloud-based delegation solutions require that only the user who has registered in the cloud can be delegated permissions.It is not convenient when a permission is delegated to a large number of temporarily users.Therefore,some works like CapBAC delegate permissions locally in an offline way.However,this is difficult to revoke and modify the offline delegated permissions.In this work,we propose a traceable capability-based access control approach(TCAC)that can revoke and modify permissions by tracking the trajectories of permissions delegation.We define a time capability tree(TCT)that can automatically extract permissions trajectories,and we also design a new capability token to improve the permission verification,revocation and modification efficiency.The experiment results show that TCAC has less token verification and revocation/modification time than those of CapBAC and xDBAuth.TCAC can discover 73.3%unvisited users in the case of delegating and accessing randomly.This provides more information about the permissions delegation relationships,and opens up new possibilities to guarantee the global security in IoT delegation system.To the best of our knowledge,TCAC is the first work to capture the unvisited permissions.
基金supported by the National Natural Science Foundation of China(6150340861573374)
文摘The hypersonic interception in near space is a great challenge because of the target’s unpredictable trajectory, which demands the interceptors of trajectory cluster coverage of the predicted area and optimal trajectory modification capability aiming at the consistently updating predicted impact point(PIP) in the midcourse phase. A novel midcourse optimal trajectory cluster generation and trajectory modification algorithm is proposed based on the neighboring optimal control theory. Firstly, the midcourse trajectory optimization problem is introduced; the necessary conditions for the optimal control and the transversality constraints are given.Secondly, with the description of the neighboring optimal trajectory existence theory(NOTET), the neighboring optimal control(NOC)algorithm is derived by taking the second order partial derivations with the necessary conditions and transversality conditions. The revised terminal constraints are reversely integrated to the initial time and the perturbations of the co-states are further expressed with the states deviations and terminal constraints modifications.Thirdly, the simulations of two different scenarios are carried out and the results prove the effectiveness and optimality of the proposed method.
