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排序方式: 共有432条查询结果,搜索用时 15 毫秒
41.
为解决复杂环境下的无人机航迹规划问题,提出了一种多重启发蚁群优化算法.该算法综合考虑无人机当前位置与待选位置之间的距离和威胁分布,以及待选位置与目标位置之间的距离和威胁分布,将这些已知信息构造为蚂蚁状态转移的多重启发信息,指导蚂蚁的搜索行为.文中对多重启发蚁群优化算法的收敛性进行了分析,并针对航迹不可行和任务区域内存在... 相似文献
42.
面向建筑健康的高时效监测需求,为提升表面病害视觉检测的自动化水平,提出了场景信息引导的无人机自主巡检任务规划方法。利用场景先验信息,针对建筑结构特征,设计了平行观测和包络观测两种观测模式,实现了狭窄空间中独栋建筑的全覆盖避障巡检,获取了毫米级分辨率的整体建筑观测影像,并对巡检质量的整体评估提出了有效的量化指标。将建筑立面划分为3 720个子区域,利用深度残差网络开展了裂缝识别分类。错分13个子区域,漏分14个子区域,裂缝识别精度高。将裂缝骨架线映射到建筑三维模型,为裂缝形态与建筑整体的一体化表达提供了数据支撑。该研究将高精度三维重建与表面病害识别相结合,为建筑健康一体化监测提供了有效的观测分析手段。 相似文献
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We consider the problem of autonomously controlling a fixed-wing aerial vehicle to visit a neighborhood of a pre-defined waypoint, and when nearby it, loiter around it. To solve this problem, we propose a hybrid feedback control strategy that unites two state-feedback controllers: a transit controller capable of steering or transitioning the vehicle to nearby the waypoint and a loiter controller capable of steering the vehicle about a loitering radius. The aerial vehicle is modeled on a level flight plane with system performance characterized in terms of the aerodynamic, propulsion, and mass properties. Thrust and bank angle are the control inputs. Asymptotic stability properties of the individual control algorithms, which are designed using backstepping, as well as of the closed-loop system, which includes a hybrid algorithm uniting the two controllers, are established. In particular, for this application of hybrid feedback control, Lyapunov functions and hybrid systems theory are employed to establish stability properties of the set of points defining loitering. The analytical results are confirmed numerically by simulations. 相似文献
45.
数据链是无人机的重要分系统,是确保无人机实现地空通信的关键一环,但容易受到外界电磁干扰的影响而发生通信中断甚至硬件损伤.针对某型无人机数据链的前门耦合电磁敏感特性,对数据链设备进行电磁干扰的等效注入试验,研究了单频和双频电磁干扰对数据链的效应规律,得到了数据链敏感频点的失锁阈值以及误码率和信噪比的变化趋势.研究表明:由于大功率干扰信号通过自动增益控制电路,在射频前端降低了中频工作信号的输出功率,导致数据终端信噪比降低、误码率上升;当双频干扰均位于带内时,与单频干扰相比,在射频前端对工作信号增益的压缩作用更强,导致失锁时双频干扰中的任意一个干扰功率均低于只有单频干扰时的阈值,表明数据链带内干扰存在多源非线性增强效应. 相似文献
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Object detection is challenging in large-scale images captured by unmanned aerial vehicles (UAVs), especially when detecting small objects with significant scale variation. Most solutions employ the fusion of different scale features by building multi-scale feature pyramids to ensure that the detail and semantic information are abundant. Although feature fusion benefits object detection, it still requires the long-range dependencies information necessary for small objects with significant scale variation detection. We propose a simple yet effective scale enhancement pyramid network (SEPNet) to address these problems. A SEPNet consists of a context enhancement module (CEM) and feature alignment module (FAM). Technically, the CEM combines multi-scale atrous convolution and multi-branch grouped convolution to model global relationships. Additionally, it enhances object feature representation, preventing features with lost spatial information from flowing into the feature pyramid network (FPN). The FAM adaptively learns offsets of pixels to preserve feature consistency. The FAM aims to adjust the location of sampling points in the convolutional kernel, effectively alleviating information conflict caused by the fusion of adjacent features. Results indicate that the SEPNet achieves an AP score of 18.9% on VisDrone, which is 7.1% higher than the AP score of state-of-the-art detectors RetinaNet achieves an AP score of 81.5% on PASCAL VOC. 相似文献
48.
Hao-Yuan Zhang Tong-Tong Zeng Zhen-Biao Xie Ying-Ying Dong Cha Ma Shan-Shan Gong Qi Sun 《Molecules (Basel, Switzerland)》2022,27(21)
In the past decade, selenocyclization has been extensively exploited for the preparation of a wide range of selenylated heterocycles with versatile activities. Previously, selenium electrophile-based and FeCl3-promoted methods were employed for the synthesis of selenylated benzoxazines. However, these methods are limited by starting material availability and low atomic economy, respectively. Inspired by the recent catalytic selenocyclization approaches based on distinctive pathways, we rationally constructed an efficient and greener double-redox catalytic system for the access to diverse selenylated benzoxazines. The coupling of I2/I− and Fe3+/Fe2+ catalytic redox cycles enables aerial O2 to act as the driving force to promote the selenocyclization. Control and test redox experiments confirmed the roles of each component in the catalytic system, and a PhSeI-based pathway is proposed for the selenocyclization process. 相似文献
49.
为满足密集分布用户的服务质量和体验质量,建立了车辆和无人机协助下的多接入边缘计算卸载模型,车辆、无人机和路边单元作为边缘节点,将不同的计算任务按需卸载到不同类型的边缘节点进行处理.设计了基于分布式匹配-贪婪算法的终端用户任务卸载方案以最小化系统功耗,并研究了用户数量和延迟容忍对卸载方案的影响.仿真结果表明:该方案在满足... 相似文献
50.
对当前我国女子佩剑运动项目的队伍建设、大赛成绩和技、战术特点进行了调查分析,指出该项目发展存在的问题,提出解决这些问题的若干建议,以促进该项目赶上世界先进水平。 相似文献