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
Although the joint-detection-and-tracking paradigm has promoted the development of multi-object tracking(MOT)significantly,the long-term occlusion problem is still unsolved.After a period of trajectory inactivation du...Although the joint-detection-and-tracking paradigm has promoted the development of multi-object tracking(MOT)significantly,the long-term occlusion problem is still unsolved.After a period of trajectory inactivation due to occlusion,it is difficult to achieve trajectory reconnection with appearance features because they are no longer reliable.Although using motion cues does not suffer from occlusion,the commonly used Kalman Filter is also ineffective in its long-term inertia prediction in cases of no observation updates or wrong updates.Besides,occlusion is prone to cause multiple track-detection pairs to have close similarity scores during the data association phase.The direct use of the Hungarian algorithm to give the global optimal solution may generate the identity switching problem.In this paper,we propose the Long-term Spatio-Temporal Prediction(LSTP)module and the Ordered Association(OA)module to alleviate the occlusion problem in terms of motion prediction and data association,respectively.The LSTP module estimates the states of all tracked objects over time using a combination of spatial and temporal Transformers.The spatial Transformer models crowd interaction and learns the influence of neighbors,while the temporal Transformer models the temporal continuity of historical trajectories.Besides,the LSTP module also predicts the visibilities of the motion prediction boxes,which denote the occlusion attributes of trajectories.Based on the occlusion attribute and active state,the association priority is defined in the OA module to associate trajectories in order,which helps to alleviate the identity switching problem.Comprehensive experiments on the MOT17 and MOT20 benchmarks indicate the superiority of the proposed MOT framework,namely Occlusion-Robust Tracker(ORT).Without using any appearance information,our ORT can achieve competitive performance beyond other state-of-the-art trackers in terms of trajectory accuracy and purity.展开更多
Underground urban expressways are a possibility for solving many existing transportation-related problems, such as traffic congestion in high density areas and the division of neighborhoods due to elevated roadways. H...Underground urban expressways are a possibility for solving many existing transportation-related problems, such as traffic congestion in high density areas and the division of neighborhoods due to elevated roadways. However, they may also pose high risks regarding traffic safety. Therefore, it is important for a pre-analysis of traffic safety to be made. This paper describes recent efforts to develop a driving simulation system, MOVIC-T4, for traffic safety analysis of underground urban expressways. In order to develop a small portable simulator, a small-sized motion-base with two-degrees-of-freedom is used to duplicate acceleration cueing together with a head-mounted-display （HMD） for the visual system. An overview of this system is given and the reliability of driving data obtained from the experiments using MOVIC-T4 is discussed through a validation study using field driving data. The results of validation indicate that the perceived speed distance headway, and physiological data in the simulator show the almost same trend as that in the real world, but larger decelerations tend to be produced in the simulator.展开更多
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.
基金supported by the National Key Laboratory Foundation of Science and Technology on Multispectral Information Processing(6142113220208)Science and Technology Plan Project of Jinan(202214002)National Natural Science Foundation of China(61105006).
文摘Although the joint-detection-and-tracking paradigm has promoted the development of multi-object tracking(MOT)significantly,the long-term occlusion problem is still unsolved.After a period of trajectory inactivation due to occlusion,it is difficult to achieve trajectory reconnection with appearance features because they are no longer reliable.Although using motion cues does not suffer from occlusion,the commonly used Kalman Filter is also ineffective in its long-term inertia prediction in cases of no observation updates or wrong updates.Besides,occlusion is prone to cause multiple track-detection pairs to have close similarity scores during the data association phase.The direct use of the Hungarian algorithm to give the global optimal solution may generate the identity switching problem.In this paper,we propose the Long-term Spatio-Temporal Prediction(LSTP)module and the Ordered Association(OA)module to alleviate the occlusion problem in terms of motion prediction and data association,respectively.The LSTP module estimates the states of all tracked objects over time using a combination of spatial and temporal Transformers.The spatial Transformer models crowd interaction and learns the influence of neighbors,while the temporal Transformer models the temporal continuity of historical trajectories.Besides,the LSTP module also predicts the visibilities of the motion prediction boxes,which denote the occlusion attributes of trajectories.Based on the occlusion attribute and active state,the association priority is defined in the OA module to associate trajectories in order,which helps to alleviate the identity switching problem.Comprehensive experiments on the MOT17 and MOT20 benchmarks indicate the superiority of the proposed MOT framework,namely Occlusion-Robust Tracker(ORT).Without using any appearance information,our ORT can achieve competitive performance beyond other state-of-the-art trackers in terms of trajectory accuracy and purity.
基金Supported by Ministry of Land, Infrastructure and Transport, Japan Society of the Promotion of Science and Mitsui Sumitomo Insurance Welfare Foundation
文摘Underground urban expressways are a possibility for solving many existing transportation-related problems, such as traffic congestion in high density areas and the division of neighborhoods due to elevated roadways. However, they may also pose high risks regarding traffic safety. Therefore, it is important for a pre-analysis of traffic safety to be made. This paper describes recent efforts to develop a driving simulation system, MOVIC-T4, for traffic safety analysis of underground urban expressways. In order to develop a small portable simulator, a small-sized motion-base with two-degrees-of-freedom is used to duplicate acceleration cueing together with a head-mounted-display （HMD） for the visual system. An overview of this system is given and the reliability of driving data obtained from the experiments using MOVIC-T4 is discussed through a validation study using field driving data. The results of validation indicate that the perceived speed distance headway, and physiological data in the simulator show the almost same trend as that in the real world, but larger decelerations tend to be produced in the simulator.
