This paper proposes a motion-based region growing segmentation scheme for the object-based video coding, which segments an image into homogeneous regions characterized by a coherent motion. It adopts a block matching ...This paper proposes a motion-based region growing segmentation scheme for the object-based video coding, which segments an image into homogeneous regions characterized by a coherent motion. It adopts a block matching algorithm to estimate motion vectors and uses morphological tools such as open-close by reconstruction and the region-growing version of the watershed algorithm for spatial segmentation to improve the temporal segmentation. In order to determine the reliable motion vectors, this paper also proposes a change detection algorithm and a multi-candidate pro- screening motion estimation method. Preliminary simulation results demonstrate that the proposed scheme is feasible. The main advantage of the scheme is its low computational load.展开更多
In this study, we report a spindle-like micromotor. This device, which is fabricated using a one-step electrospinning method, consists of biodegradable polycaprolactone and an anionic surfactant. Intriguingly, not onl...In this study, we report a spindle-like micromotor. This device, which is fabricated using a one-step electrospinning method, consists of biodegradable polycaprolactone and an anionic surfactant. Intriguingly, not only can the resulting micromotor move autonomously on the surface of water for a long period of time （-40 min） due to the Marangoni effect, but it also exhibits a pH sensing behavior due to variations in the surface tension caused by the release of surfactant under different pH conditions. More interestingly, we reveal that the motion-based pH sensing property is size-dependent, with smaller structures exhibiting a higher sensitivity. In addition, since polycaprolactone is a biode- gradable material, the micromotor described in this study can be easily degraded in solution. Hence, features such as one-step fabrication, motion readout, and biodegradability render this micromotor an attractive candidate for sensing algplications.展开更多
Sustaining awkward postures and overexertion are common factors in construction industry that result in work-related injuries of workers. To address there safety and health issues, conventional observational methods o...Sustaining awkward postures and overexertion are common factors in construction industry that result in work-related injuries of workers. To address there safety and health issues, conventional observational methods on the external causes are tedious and subjective, while the direct measurement on the internal causes is intrusive leading to productivity reduction. Therefore, it is essential to construct an effective approach that maps the external and internal causes to realize the non-intrusive identification of safety and health risks. This research proposes a theoretical method to analyze the postures tracked by videos with biomechanical models. Through the biomechanical skeleton representation of human body, the workload and joint torques are rapidly and accurately evaluated based on the rotation angles of joints. The method is then demonstrated by two case studies about(1) plastering and(2) carrying. The experiment results illustrate the changing intramuscular torques across the construction activities in essence, validating the proposed approach to be effective in theory.展开更多
在视觉SLAM(Simultaneous Localization and Mapping)系统中,特征匹配对实时定位与建图起着重要作用。ORB-SLAM3系统面临特征匹配效率不高且缺乏稠密地图构建能力的问题,针对该问题文章提出了一种融合网格运动统计策略和稠密建图能力的...在视觉SLAM(Simultaneous Localization and Mapping)系统中,特征匹配对实时定位与建图起着重要作用。ORB-SLAM3系统面临特征匹配效率不高且缺乏稠密地图构建能力的问题,针对该问题文章提出了一种融合网格运动统计策略和稠密建图能力的算法ORB-SLAM3-GD(ORB-SLAM3 with GMS Strategy and Dense Mapping)。新算法在特征匹配阶段,通过比较特征点邻域内的匹配点数量和阈值筛选正确匹配以提升匹配准确率,并引入稠密点云构建线程生成稠密点云地图,在生成地图的过程中采用外点剔除滤波与体素网格滤波技术压缩点云规模。在TUM(Technical University of Munich,TUM)数据集上进行性能评估测试,结果表明:相比ORB-SLAM3,文章所提算法平均匹配点数提升了61.7%,匹配时间缩短45.61%,绝对轨迹误差平均降低21.62%,体现了新算法的优势。展开更多
文摘This paper proposes a motion-based region growing segmentation scheme for the object-based video coding, which segments an image into homogeneous regions characterized by a coherent motion. It adopts a block matching algorithm to estimate motion vectors and uses morphological tools such as open-close by reconstruction and the region-growing version of the watershed algorithm for spatial segmentation to improve the temporal segmentation. In order to determine the reliable motion vectors, this paper also proposes a change detection algorithm and a multi-candidate pro- screening motion estimation method. Preliminary simulation results demonstrate that the proposed scheme is feasible. The main advantage of the scheme is its low computational load.
基金Acknowledgements This work is supported by the National Natural Science Foundation of China （Nos. 21574094 and 21304064）, the Natural Science Foundation of Jiangsu Province （Nos. BK20130292 and BK20150314）, a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions （PAPD）, the Fund for Excellent Creative Research Teams of Jiangsu Higher Education Institutions and the projectsponsored by the Scientific Research Foundation for the returned overseas Chinese scholars, State Education Ministry.
文摘In this study, we report a spindle-like micromotor. This device, which is fabricated using a one-step electrospinning method, consists of biodegradable polycaprolactone and an anionic surfactant. Intriguingly, not only can the resulting micromotor move autonomously on the surface of water for a long period of time （-40 min） due to the Marangoni effect, but it also exhibits a pH sensing behavior due to variations in the surface tension caused by the release of surfactant under different pH conditions. More interestingly, we reveal that the motion-based pH sensing property is size-dependent, with smaller structures exhibiting a higher sensitivity. In addition, since polycaprolactone is a biode- gradable material, the micromotor described in this study can be easily degraded in solution. Hence, features such as one-step fabrication, motion readout, and biodegradability render this micromotor an attractive candidate for sensing algplications.
文摘Sustaining awkward postures and overexertion are common factors in construction industry that result in work-related injuries of workers. To address there safety and health issues, conventional observational methods on the external causes are tedious and subjective, while the direct measurement on the internal causes is intrusive leading to productivity reduction. Therefore, it is essential to construct an effective approach that maps the external and internal causes to realize the non-intrusive identification of safety and health risks. This research proposes a theoretical method to analyze the postures tracked by videos with biomechanical models. Through the biomechanical skeleton representation of human body, the workload and joint torques are rapidly and accurately evaluated based on the rotation angles of joints. The method is then demonstrated by two case studies about(1) plastering and(2) carrying. The experiment results illustrate the changing intramuscular torques across the construction activities in essence, validating the proposed approach to be effective in theory.
文摘在视觉SLAM(Simultaneous Localization and Mapping)系统中,特征匹配对实时定位与建图起着重要作用。ORB-SLAM3系统面临特征匹配效率不高且缺乏稠密地图构建能力的问题,针对该问题文章提出了一种融合网格运动统计策略和稠密建图能力的算法ORB-SLAM3-GD(ORB-SLAM3 with GMS Strategy and Dense Mapping)。新算法在特征匹配阶段,通过比较特征点邻域内的匹配点数量和阈值筛选正确匹配以提升匹配准确率,并引入稠密点云构建线程生成稠密点云地图,在生成地图的过程中采用外点剔除滤波与体素网格滤波技术压缩点云规模。在TUM(Technical University of Munich,TUM)数据集上进行性能评估测试,结果表明:相比ORB-SLAM3,文章所提算法平均匹配点数提升了61.7%,匹配时间缩短45.61%,绝对轨迹误差平均降低21.62%,体现了新算法的优势。
文摘为应对开放自动化与云化控制趋势,本文探索了5G与EtherCAT融合的云化运动控制系统架构.针对云化可编程逻辑控制器(Programmable logic controller,PLC)与现场设备在5G网络下的连接难题,提出一种基于虚拟扩展局域网(Virtual eXtensible local area network,VxLAN)的融合组网方案,通过网络虚拟化技术实现EtherCAT数据的透明传输.其次,鉴于5G与专用工业协议存在显著性能差异,本文通过量化分析方法揭示了网络时延抖动影响运动控制稳定性的内在机理,建立了系统稳定运行周期与关键网络性能指标间的数学约束模型.最后,在真实5G网络环境下搭建了实验平台,通过与有线网络对比测试,验证了所提融合架构的通用性与约束模型的有效性.本研究不仅为传统工控系统的云化改造提供了可行的实施方案,更重要的是,提出了针对无线网络承载工控任务稳定性的分析方法与评估手段.
