The application of soft pneumatic actuators is typically hindered by the low strength and slow response speed caused by their intrinsic material limitation and unstressed stable form.In this work,we present a design s...The application of soft pneumatic actuators is typically hindered by the low strength and slow response speed caused by their intrinsic material limitation and unstressed stable form.In this work,we present a design strategy for improving the performance and response speed for Pneu-Nets actuators by incorporating adjustable elastic components to form the elastic composite pneumatic actuator(ECPA).The elastic energy storage of the elastic component is implemented to enhance the capability and speed up the response of ECPA and pre-bend the actuator.Due to the design principle,the fully-flexible ECPA is easy to manufacture and regulate.Theoretical modeling and experiments are implemented to reveal the fast response characteristics and adjustable mechanical characteristics of ECPA.Experimental results show that the deflation response speed of ECPA is increased by at least 3.1 times with the action of elastic components,what is more,the stiffness of ECPA is increased by 22 times.Based on the ECPA,two kinds of locomotion robots including a running robot(runs at an average locomotion speed of 6.3 BL/s(body lengths,BL))and an underwater swimming robot(achieves an average speed of 1.1 BL/s)are designed.The fast-moving robots both demonstrate high-speed mobility because of the rapid response and high strength of ECPA.展开更多
Simultaneous multicolor photometry of fast-moving objects is discussed in this paper. In conventional astronomical photometry, the accuracy of flux and color indices of fast-moving objects is affected by the variation...Simultaneous multicolor photometry of fast-moving objects is discussed in this paper. In conventional astronomical photometry, the accuracy of flux and color indices of fast-moving objects is affected by the variations of the targets and weather conditions in space and time domains.We optimize related techniques and methods of observation and data reduction, including image cal- ibration, background fitting, targets detection and location, isophotal photometry, and flux calibration by using background stars from different fields. We consider that simultaneous multicolor data acquisition and differential flux calibration are critical for improving photometric accuracy of fast-moving objects. Our results show the photometric accuracy is better than 5% based on the observations carried out by a 1-meter telescope under ordinary, non-photometric conditions.展开更多
The ionospheric effect plays a crucial role in the radio communications. For ionospheric observing and monitoring, the Global Navigation Satellite System (GNSS) has been widely utilized. The ionospheric condition can ...The ionospheric effect plays a crucial role in the radio communications. For ionospheric observing and monitoring, the Global Navigation Satellite System (GNSS) has been widely utilized. The ionospheric condition can be characterized by the Total Electron Contents (TEC) and TEC Rate (TECR) calculated from the GNSS measurements. Currently, GNSS-based ionospheric observing and monitoring largely depend on a global fiducial network of GNSS receivers such as the International GNSS Service (IGS) network. We propose a new approach to observe the ionosphere by deploying a GNSS receiver on a Hong Kong Mass Transit Railway (MTR) train. We assessed the TECR derived from the MTR-based GNSS receiver by comparing it with the TECR derived from a static GNSS receiver. The results show that the Root-Mean-Squares (RMS) errors of the TECR derived from the MTR-based GNSS receiver is consistently approxi-mately 23% higher than that derived from the static GNSS receiver. Despite the increased error, the findings suggest that the GNSS observation on a fast-moving platform is a feasible approach to observe the ionosphere over a large region in a rapid and cost-effective way.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.91748118 and 12032015)the Program of Shanghai Key Laboratory of Spacecraft Mechanism+2 种基金the National Natural Science Foundation for Distinguished Young Scholars of China(Grant No.11625208)the Program of Shanghai Academic/Technology Research Leader(Grant No.19XD1421600)the National Postdoctoral Program for Innovative Talents(Grant No.BX20190201)。
文摘The application of soft pneumatic actuators is typically hindered by the low strength and slow response speed caused by their intrinsic material limitation and unstressed stable form.In this work,we present a design strategy for improving the performance and response speed for Pneu-Nets actuators by incorporating adjustable elastic components to form the elastic composite pneumatic actuator(ECPA).The elastic energy storage of the elastic component is implemented to enhance the capability and speed up the response of ECPA and pre-bend the actuator.Due to the design principle,the fully-flexible ECPA is easy to manufacture and regulate.Theoretical modeling and experiments are implemented to reveal the fast response characteristics and adjustable mechanical characteristics of ECPA.Experimental results show that the deflation response speed of ECPA is increased by at least 3.1 times with the action of elastic components,what is more,the stiffness of ECPA is increased by 22 times.Based on the ECPA,two kinds of locomotion robots including a running robot(runs at an average locomotion speed of 6.3 BL/s(body lengths,BL))and an underwater swimming robot(achieves an average speed of 1.1 BL/s)are designed.The fast-moving robots both demonstrate high-speed mobility because of the rapid response and high strength of ECPA.
文摘Simultaneous multicolor photometry of fast-moving objects is discussed in this paper. In conventional astronomical photometry, the accuracy of flux and color indices of fast-moving objects is affected by the variations of the targets and weather conditions in space and time domains.We optimize related techniques and methods of observation and data reduction, including image cal- ibration, background fitting, targets detection and location, isophotal photometry, and flux calibration by using background stars from different fields. We consider that simultaneous multicolor data acquisition and differential flux calibration are critical for improving photometric accuracy of fast-moving objects. Our results show the photometric accuracy is better than 5% based on the observations carried out by a 1-meter telescope under ordinary, non-photometric conditions.
基金the Key Program of the National Natural Science Foundation of China(NSFC)project(No.:41730109)is acknowledgedThe grant supports to Zhizhao Liu from the Hong Kong Research Grants Council(RGC)project(B-Q61L PolyU 152222/17E)are thankedThe Emerging Frontier Area(EFA)Scheme of Research Institute for Sustainable Urban Development(RISUD)of the Hong Kong Polytechnic University under Grant 1-BBWJ is also acknowledged.
文摘The ionospheric effect plays a crucial role in the radio communications. For ionospheric observing and monitoring, the Global Navigation Satellite System (GNSS) has been widely utilized. The ionospheric condition can be characterized by the Total Electron Contents (TEC) and TEC Rate (TECR) calculated from the GNSS measurements. Currently, GNSS-based ionospheric observing and monitoring largely depend on a global fiducial network of GNSS receivers such as the International GNSS Service (IGS) network. We propose a new approach to observe the ionosphere by deploying a GNSS receiver on a Hong Kong Mass Transit Railway (MTR) train. We assessed the TECR derived from the MTR-based GNSS receiver by comparing it with the TECR derived from a static GNSS receiver. The results show that the Root-Mean-Squares (RMS) errors of the TECR derived from the MTR-based GNSS receiver is consistently approxi-mately 23% higher than that derived from the static GNSS receiver. Despite the increased error, the findings suggest that the GNSS observation on a fast-moving platform is a feasible approach to observe the ionosphere over a large region in a rapid and cost-effective way.
