An optimal burst height is required for the fly-over and shoot-down smart ammunition with an EFP warhead at the instant of explosion which brings a special requirement to the miss distance of the terminal guidance law...An optimal burst height is required for the fly-over and shoot-down smart ammunition with an EFP warhead at the instant of explosion which brings a special requirement to the miss distance of the terminal guidance law. In this paper, a guidance law based on the virtual target scheme is proposed. First, the practical pursuit-evasion issue between the ammunition and the target with specific miss distance is transformed into a virtuai pursuit-evasion problem with zero miss distance. Secondly, a complete three-dimensional pursuit-evasion kinematics model is established without any simplifications. And then, a suboptimal guidance law is designed based on the θ-D method which has constraints of the elevation and azimuth angular velocity of the virtual line of sight （LOS）. Finally, in order to verify the performance of the proposed guidance law, three test cases are conducted. Numericai results show that under the proposed terminal guidance law, the smart ammunition not only can fly above the target with an optimal burst height but also have a smaller normal acceleration on the terminal trajectory.展开更多
We describe a user interface and interaction technique,named'Javelin',designed for large display environments.It provides quick access to random screen regions and manipulation methods for screen widgets which...We describe a user interface and interaction technique,named'Javelin',designed for large display environments.It provides quick access to random screen regions and manipulation methods for screen widgets which are difficult or impossible to reach.It consists of a dynamic global thumbnail,a touchpad widget that drives the screen cursor,and a teleport widget in which interactions are transferred to its target screen region.Javelin can be easily integrated into many programs to optimize their interaction performance in large screens.The experiment and user study show that Javelin can extend user access field and enhance widget manipulation in large displays.展开更多
基金Supported by the Fundamental Scientific Research Program of China Ministries and Commissions(B2220132013)
文摘An optimal burst height is required for the fly-over and shoot-down smart ammunition with an EFP warhead at the instant of explosion which brings a special requirement to the miss distance of the terminal guidance law. In this paper, a guidance law based on the virtual target scheme is proposed. First, the practical pursuit-evasion issue between the ammunition and the target with specific miss distance is transformed into a virtuai pursuit-evasion problem with zero miss distance. Secondly, a complete three-dimensional pursuit-evasion kinematics model is established without any simplifications. And then, a suboptimal guidance law is designed based on the θ-D method which has constraints of the elevation and azimuth angular velocity of the virtual line of sight （LOS）. Finally, in order to verify the performance of the proposed guidance law, three test cases are conducted. Numericai results show that under the proposed terminal guidance law, the smart ammunition not only can fly above the target with an optimal burst height but also have a smaller normal acceleration on the terminal trajectory.
基金Project supported by China Academic Digital Associative Library (CADAL)
文摘We describe a user interface and interaction technique,named'Javelin',designed for large display environments.It provides quick access to random screen regions and manipulation methods for screen widgets which are difficult or impossible to reach.It consists of a dynamic global thumbnail,a touchpad widget that drives the screen cursor,and a teleport widget in which interactions are transferred to its target screen region.Javelin can be easily integrated into many programs to optimize their interaction performance in large screens.The experiment and user study show that Javelin can extend user access field and enhance widget manipulation in large displays.
