This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency sh...This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency shift and path difference,the virtual path difference is calculated from the measured value of Doppler frequency shift by means of mean value correction.Then,under the assumption that the target is moving at a constant speed along a straight line,two coaxial virtual double base arrays are constructed by using the moving track of the moving target based on the method of fixed period time difference.On this basis,the moving distance of the moving target can be calculated by using the ratio relationship between the frequency difference and the radial distance between the two adjacent detection points in the middle of the array,and the linear solution of the two double base path difference positioning equations.At this point,the relative coordinate position of the moving target can be obtained by directly using the linear solution of the double base path difference positioning equation again.展开更多
Virtual path concept has several valuable features to re construct an economical and efficient ATM network.The most important effect of VPs is to afford transmission efficiently through the dynamic control of VPs reso...Virtual path concept has several valuable features to re construct an economical and efficient ATM network.The most important effect of VPs is to afford transmission efficiently through the dynamic control of VPs resource including buffer and bandwidth.This paper described the problem of dynamic resource control of VP in ATM networks.Based on a discrete event dynamic model of resource control of VP in ATM networks,the optimal control law of resource allocation of VP in ATM networks with the method of dynamic programming was presented.The results of the theorem proof and simulation show that the dynamic control is more efficient to reduce the calls block rate comparing with the static allocation.展开更多
This article proposes a novel fuzzy virtual force （FVF） method for unmanned aerial vehicle （UAV） path planning in compli-cated environment. An integrated mathematical model of UAV path planning based on virtual fo...This article proposes a novel fuzzy virtual force （FVF） method for unmanned aerial vehicle （UAV） path planning in compli-cated environment. An integrated mathematical model of UAV path planning based on virtual force （VF） is constructed and the corresponding optimal solving method under the given indicators is presented. Specifically,a fixed step method is developed to reduce computational cost and the reachable condition of path planning is proved. The Bayesian belief network and fuzzy logic reasoning theories are applied to setting the path planning parameters adaptively,which can reflect the battlefield situation dy-namically and precisely. A new way of combining threats is proposed to solve the local minima problem completely. Simulation results prove the feasibility and usefulness of using FVF for UAV path planning. Performance comparisons between the FVF method and the A＊ search algorithm demonstrate that the proposed approach is fast enough to meet the real-time requirements of the online path planning problems.展开更多
Although computer capabilities have been improved significantly, a large-scale virtual reality （VR） system demands much more in terms of memory and computation than the current computer systems can offer. This paper...Although computer capabilities have been improved significantly, a large-scale virtual reality （VR） system demands much more in terms of memory and computation than the current computer systems can offer. This paper discusses two important issues related to VR performance and applications in building navigation. These are dynamic loading of models based on cell segmentation for the optimal VR operation, and the route optimization based on path planning for easy navigation. The VR model of engineering and information technology complex （EITC） building at the University of Manitoba is built as an example to show the feasibility of the proposed methods. The reality, enhanced by three-dimensional （3D） real-time interactivity and visualization, leads navigators into a state of the virtual building immersion.展开更多
面向无人机智能巡检的桥梁数字孪生系统需要集成与处理增量式的多模态数据,以支撑面向现实场景动态决策的高精度仿真需求。然而,现有数字孪生平台时空数据管理割裂、多模态数据融合不足、决策交互机制缺失,并未形成真正意义上的面向无...面向无人机智能巡检的桥梁数字孪生系统需要集成与处理增量式的多模态数据,以支撑面向现实场景动态决策的高精度仿真需求。然而,现有数字孪生平台时空数据管理割裂、多模态数据融合不足、决策交互机制缺失,并未形成真正意义上的面向无人机智能巡检的桥梁数字孪生系统。基于此,提出了一种融合IFC (Industry Foundation Classes)、知识图谱和游戏引擎的桥梁数字孪生系统。系统以基于IFC构建的知识图谱(IFC-graph)为核心的数据管理引擎,统一整合桥梁设计建造信息、无人机巡检规划所需的结构语义,以及巡检过程中获取的多模态感知数据(如点云、图像等),构建覆盖构件-子结构-区域等多空间尺度、支持全生命周期演化的增量式语义管理体系,并实现语义驱动下的高效信息检索与动态数据关联。在虚拟仿真层面,系统引入虚幻引擎构建高保真三维桥梁环境,精准复刻物理场景中的几何结构与环境要素,并通过与IFC知识图谱的双向联动机制,支持无人机路径规划、飞行策略模拟与多轮次巡检任务的交互式推演,能够真实还原飞行过程中的转向、避障与碰撞等复杂行为。基于上述系统框架,进一步提出一种融合构件语义的无人机巡检路径优化算法,有效提升路径规划的适应性与精度,实现面向关键构件的高分辨率检测。系统已在实际桥梁案例中完成部署与验证,结果表明:该方案具备良好的可扩展性与工程适用性,可为桥梁运维过程中的智能化分析与全生命周期管理提供新型解决思路与技术支撑。展开更多
We present a new algorithm to compute a geodesic path over a triangle mesh. Based on Novotni＇s propagating wavefront method which is similar to the well known Dijkstra algorithm, we made some improvements which Novot...We present a new algorithm to compute a geodesic path over a triangle mesh. Based on Novotni＇s propagating wavefront method which is similar to the well known Dijkstra algorithm, we made some improvements which Novotni had missed and we also gave the method to find out the geodesic path which Novotni had not. It can handle both convex and non-convex surfaces or even with boundaries. Experiment results show that our method works very well both in efficiency and precision.展开更多
文摘This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency shift and path difference,the virtual path difference is calculated from the measured value of Doppler frequency shift by means of mean value correction.Then,under the assumption that the target is moving at a constant speed along a straight line,two coaxial virtual double base arrays are constructed by using the moving track of the moving target based on the method of fixed period time difference.On this basis,the moving distance of the moving target can be calculated by using the ratio relationship between the frequency difference and the radial distance between the two adjacent detection points in the middle of the array,and the linear solution of the two double base path difference positioning equations.At this point,the relative coordinate position of the moving target can be obtained by directly using the linear solution of the double base path difference positioning equation again.
文摘Virtual path concept has several valuable features to re construct an economical and efficient ATM network.The most important effect of VPs is to afford transmission efficiently through the dynamic control of VPs resource including buffer and bandwidth.This paper described the problem of dynamic resource control of VP in ATM networks.Based on a discrete event dynamic model of resource control of VP in ATM networks,the optimal control law of resource allocation of VP in ATM networks with the method of dynamic programming was presented.The results of the theorem proof and simulation show that the dynamic control is more efficient to reduce the calls block rate comparing with the static allocation.
基金National Natural Science Foundation of China (60975073)Aeronautical Science Foundation of China (2008ZC13011)+1 种基金Research Foundation for Doctoral Program of Higher Education of China (20091102110006)Fundamental Research Funds for the Central Universities
文摘This article proposes a novel fuzzy virtual force （FVF） method for unmanned aerial vehicle （UAV） path planning in compli-cated environment. An integrated mathematical model of UAV path planning based on virtual force （VF） is constructed and the corresponding optimal solving method under the given indicators is presented. Specifically,a fixed step method is developed to reduce computational cost and the reachable condition of path planning is proved. The Bayesian belief network and fuzzy logic reasoning theories are applied to setting the path planning parameters adaptively,which can reflect the battlefield situation dy-namically and precisely. A new way of combining threats is proposed to solve the local minima problem completely. Simulation results prove the feasibility and usefulness of using FVF for UAV path planning. Performance comparisons between the FVF method and the A＊ search algorithm demonstrate that the proposed approach is fast enough to meet the real-time requirements of the online path planning problems.
基金supported by Discovery Grants of National Science and Engineering Research Council of Canada (NSERC) and Faculty of Engineering at University of Manitoba
文摘Although computer capabilities have been improved significantly, a large-scale virtual reality （VR） system demands much more in terms of memory and computation than the current computer systems can offer. This paper discusses two important issues related to VR performance and applications in building navigation. These are dynamic loading of models based on cell segmentation for the optimal VR operation, and the route optimization based on path planning for easy navigation. The VR model of engineering and information technology complex （EITC） building at the University of Manitoba is built as an example to show the feasibility of the proposed methods. The reality, enhanced by three-dimensional （3D） real-time interactivity and visualization, leads navigators into a state of the virtual building immersion.
文摘面向无人机智能巡检的桥梁数字孪生系统需要集成与处理增量式的多模态数据,以支撑面向现实场景动态决策的高精度仿真需求。然而,现有数字孪生平台时空数据管理割裂、多模态数据融合不足、决策交互机制缺失,并未形成真正意义上的面向无人机智能巡检的桥梁数字孪生系统。基于此,提出了一种融合IFC (Industry Foundation Classes)、知识图谱和游戏引擎的桥梁数字孪生系统。系统以基于IFC构建的知识图谱(IFC-graph)为核心的数据管理引擎,统一整合桥梁设计建造信息、无人机巡检规划所需的结构语义,以及巡检过程中获取的多模态感知数据(如点云、图像等),构建覆盖构件-子结构-区域等多空间尺度、支持全生命周期演化的增量式语义管理体系,并实现语义驱动下的高效信息检索与动态数据关联。在虚拟仿真层面,系统引入虚幻引擎构建高保真三维桥梁环境,精准复刻物理场景中的几何结构与环境要素,并通过与IFC知识图谱的双向联动机制,支持无人机路径规划、飞行策略模拟与多轮次巡检任务的交互式推演,能够真实还原飞行过程中的转向、避障与碰撞等复杂行为。基于上述系统框架,进一步提出一种融合构件语义的无人机巡检路径优化算法,有效提升路径规划的适应性与精度,实现面向关键构件的高分辨率检测。系统已在实际桥梁案例中完成部署与验证,结果表明:该方案具备良好的可扩展性与工程适用性,可为桥梁运维过程中的智能化分析与全生命周期管理提供新型解决思路与技术支撑。
基金This work was supported by National Natural Science Foundation of PRC(No.60503058,No.60533080)the Science and Technology Fund of Huawei Technologies Co.,Ltd.
文摘We present a new algorithm to compute a geodesic path over a triangle mesh. Based on Novotni＇s propagating wavefront method which is similar to the well known Dijkstra algorithm, we made some improvements which Novotni had missed and we also gave the method to find out the geodesic path which Novotni had not. It can handle both convex and non-convex surfaces or even with boundaries. Experiment results show that our method works very well both in efficiency and precision.
