The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is pr...The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is prone to body freedomflutter(BFF),which is a result of coupling of the rigid body short-periodmodewith 1st wing bendingmode.Accurate prediction of the BFF characteristics is helpful to reflect the attitude changes of the vehicle intuitively and design the active flutter suppression control law.Instead of using the rigid body mode,this work simulates the rigid bodymotion of the model by using the six-degree-of-freedom(6DOF)equation.A dynamicmesh generation strategy particularly suitable for BFF simulation of free flying aircraft is developed.An accurate Computational Fluid Dynamics/Computational Structural Dynamics/six-degree-of-freedom equation(CFD/CSD/6DOF)-based BFF prediction method is proposed.Firstly,the time-domain CFD/CSD method is used to calculate the static equilibrium state of the model.Based on this state,the CFD/CSD/6DOF equation is solved in time domain to evaluate the structural response of themodel.Then combinedwith the variable stiffnessmethod,the critical flutter point of the model is obtained.This method is applied to the BFF calculation of a flyingwing model.The calculation results of the BFF characteristics of the model agree well with those fromthe modalmethod andNastran software.Finally,the method is used to analyze the influence factors of BFF.The analysis results show that the flutter speed can be improved by either releasing plunge constraint or moving the center ofmass forward or increasing the pitch inertia.展开更多
随着元宇宙概念的兴起,以6自由度(six degree of freedom,6DoF)视频为代表的新一代交互式媒体技术得到产业界和学术界的广泛关注。6DoF视频隶属于多媒体通信领域,通过计算重构的方式向用户提供包括视角、光照、焦距和视场范围等多个维...随着元宇宙概念的兴起,以6自由度(six degree of freedom,6DoF)视频为代表的新一代交互式媒体技术得到产业界和学术界的广泛关注。6DoF视频隶属于多媒体通信领域,通过计算重构的方式向用户提供包括视角、光照、焦距和视场范围等多个维度的媒体交互与内容变化,能使千里之外的用户有身临其境、千人千面之感,与元宇宙具有的感知、计算、重构、协同和交互等技术特征具有高度重合性。因此,6DoF视频涵盖的技术体系可作为实现元宇宙的替代技术框架。本文提出了6DoF视频10个方面的40个问题,并将6DoF视频端到端技术链条归纳为生成、分发和呈现3个宏观阶段,随后围绕这3个技术阶段分别从内容采集与预处理、编码压缩与传输优化以及交互与呈现等方面阐述国内外研究进展。其中,在内容采集与预处理阶段,阐述了多视点联合采集、多视点与深度联合采集、深度图与点云预处理;在视频压缩与传输阶段,阐述了多视点视频编码、多视点+深度视频编码、光场图像压缩、焦栈图像压缩、点云编码压缩、6DoF视频传输优化;在交互与显示阶段,阐述了解码后滤波增强和虚拟视点合成。最后,本文围绕该领域当下的挑战,对未来趋势进行了讨论。展开更多
基金This work was supported by the National Natural Science Foundation of China(No.11872212)and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is prone to body freedomflutter(BFF),which is a result of coupling of the rigid body short-periodmodewith 1st wing bendingmode.Accurate prediction of the BFF characteristics is helpful to reflect the attitude changes of the vehicle intuitively and design the active flutter suppression control law.Instead of using the rigid body mode,this work simulates the rigid bodymotion of the model by using the six-degree-of-freedom(6DOF)equation.A dynamicmesh generation strategy particularly suitable for BFF simulation of free flying aircraft is developed.An accurate Computational Fluid Dynamics/Computational Structural Dynamics/six-degree-of-freedom equation(CFD/CSD/6DOF)-based BFF prediction method is proposed.Firstly,the time-domain CFD/CSD method is used to calculate the static equilibrium state of the model.Based on this state,the CFD/CSD/6DOF equation is solved in time domain to evaluate the structural response of themodel.Then combinedwith the variable stiffnessmethod,the critical flutter point of the model is obtained.This method is applied to the BFF calculation of a flyingwing model.The calculation results of the BFF characteristics of the model agree well with those fromthe modalmethod andNastran software.Finally,the method is used to analyze the influence factors of BFF.The analysis results show that the flutter speed can be improved by either releasing plunge constraint or moving the center ofmass forward or increasing the pitch inertia.
文摘随着元宇宙概念的兴起,以6自由度(six degree of freedom,6DoF)视频为代表的新一代交互式媒体技术得到产业界和学术界的广泛关注。6DoF视频隶属于多媒体通信领域,通过计算重构的方式向用户提供包括视角、光照、焦距和视场范围等多个维度的媒体交互与内容变化,能使千里之外的用户有身临其境、千人千面之感,与元宇宙具有的感知、计算、重构、协同和交互等技术特征具有高度重合性。因此,6DoF视频涵盖的技术体系可作为实现元宇宙的替代技术框架。本文提出了6DoF视频10个方面的40个问题,并将6DoF视频端到端技术链条归纳为生成、分发和呈现3个宏观阶段,随后围绕这3个技术阶段分别从内容采集与预处理、编码压缩与传输优化以及交互与呈现等方面阐述国内外研究进展。其中,在内容采集与预处理阶段,阐述了多视点联合采集、多视点与深度联合采集、深度图与点云预处理;在视频压缩与传输阶段,阐述了多视点视频编码、多视点+深度视频编码、光场图像压缩、焦栈图像压缩、点云编码压缩、6DoF视频传输优化;在交互与显示阶段,阐述了解码后滤波增强和虚拟视点合成。最后,本文围绕该领域当下的挑战,对未来趋势进行了讨论。
