The net primary productivity of vegetation(NPP)is an important index to evaluate the carbon sequestration capacity of vegetation and land use change.Using MOD17N3HGF NPP data,climate data and night-time light data fro...The net primary productivity of vegetation(NPP)is an important index to evaluate the carbon sequestration capacity of vegetation and land use change.Using MOD17N3HGF NPP data,climate data and night-time light data from 2000 to 2020,this study explored the relationship between NPP and urban expansion,land use and climate change in the Southern Part of Taihang Mountain through brightness gradient method,trend analysis,partial correlation analysis and contribution analysis.It aims to provide information support for urban and rural planning and ecological management in this region.Key findings include:Over the past 20 years,NPP in mountain areas has shown an overall fluctuating upward trend,with an“N”pattern related to altitude.The human activity area expanded by 9.9%,with expansion of highly active areas holding back NPP growth and moderately active areas contributing to it.The trend of climate change is gradually warming and wetting,and the correlation between precipitation and NPP is strong,while the correlation between temperature and NPP is weak.Compared with human activities(19.9%),precipitation was the main driver of NPP change,contributing significantly up to 79.5%.In the past 20 years,the ecological quality of the south Taihang Mountain region has improved significantly and actively responded to climate change,but human activities have led to spatial and temporal ecological differences.展开更多
Aimed at the problem of final translation of space rendezvous for the applications such as docking,inspection and tracking,optimal straight-line guidance algorithm based on pulse/continuous low-thrust in the context o...Aimed at the problem of final translation of space rendezvous for the applications such as docking,inspection and tracking,optimal straight-line guidance algorithm based on pulse/continuous low-thrust in the context of Clohessy-Wiltshire dynamics is proposed.Two modes of guidance strategy:varying-speed and fixed-speed approaching scheme for V-bar and R-bar approach by using constant/finite low-thrust propulsion respectively are studied,and the corresponding fuel-optimal conditions are obtained.Numerical simulation is conducted to verify and test the proposed algorithms.The results show that there is generally no different between the fuel consumptions by using the two different approaching modes for V-bar case.However,the conclusion for Rbar case is different that the using of continuous low-thrust cost more fuel and transfer time.展开更多
As to solve the collaborative relative navigation problem for near-circular orbiting small satellites in close-range under GNSS denied environment,a novel consensus constrained relative navigation algorithm based on t...As to solve the collaborative relative navigation problem for near-circular orbiting small satellites in close-range under GNSS denied environment,a novel consensus constrained relative navigation algorithm based on the lever arm effect of the sensor offset from the spacecraft center of mass is proposed.Firstly,the orbital propagation model for the relative motion of multi-spacecraft is established based on Hill-Clohessy-Wiltshire dynamics and the line-of-sight measurement under sensor offset condition is modeled in Local Vertical Local Horizontal frame.Secondly,the consensus constraint model for the relative orbit state is constructed by introducing the geometry constraint between the spacecraft,based on which the consensus unscented Kalman filter is designed.Thirdly,the observability analysis is done and the necessary conditions of the sensor offset to make the state observable are obtained.Lastly,digital simulations are conducted to verify the proposed algorithm,where the comparison to the unconstrained case is also done.The results show that the estimated error of the relative position converges very quickly,the location error is smaller than 10m under the condition of 10−3 rad level camera and 5m offset.展开更多
基金funded by NSFC Regional Innovation Development Joint Fund Key Project(U21A20108)General Project of Natural Science Foundation of Henan Province(242300421365)+3 种基金Support Plan for Technological Innovation Teams in Henan Province’s Higher Education Institutions(22IRTSTHN008)General Project for Humanities and Social Sciences in Higher Education Institutions of Henan Province(2024ZZJH147)Co-fundedResearch Program of“Double First-class”Creation Project of Surveying and Mapping Science and Technology Discipline(GCCYJ202401).
文摘The net primary productivity of vegetation(NPP)is an important index to evaluate the carbon sequestration capacity of vegetation and land use change.Using MOD17N3HGF NPP data,climate data and night-time light data from 2000 to 2020,this study explored the relationship between NPP and urban expansion,land use and climate change in the Southern Part of Taihang Mountain through brightness gradient method,trend analysis,partial correlation analysis and contribution analysis.It aims to provide information support for urban and rural planning and ecological management in this region.Key findings include:Over the past 20 years,NPP in mountain areas has shown an overall fluctuating upward trend,with an“N”pattern related to altitude.The human activity area expanded by 9.9%,with expansion of highly active areas holding back NPP growth and moderately active areas contributing to it.The trend of climate change is gradually warming and wetting,and the correlation between precipitation and NPP is strong,while the correlation between temperature and NPP is weak.Compared with human activities(19.9%),precipitation was the main driver of NPP change,contributing significantly up to 79.5%.In the past 20 years,the ecological quality of the south Taihang Mountain region has improved significantly and actively responded to climate change,but human activities have led to spatial and temporal ecological differences.
基金State Key Laboratory of Satellite Navigation System and Equipment Technology(CEPNT-2017KF-02)the Natural Science Foundation of China(11802119)Fundamental Research Funds for Central Universities(NT2019023)。
文摘Aimed at the problem of final translation of space rendezvous for the applications such as docking,inspection and tracking,optimal straight-line guidance algorithm based on pulse/continuous low-thrust in the context of Clohessy-Wiltshire dynamics is proposed.Two modes of guidance strategy:varying-speed and fixed-speed approaching scheme for V-bar and R-bar approach by using constant/finite low-thrust propulsion respectively are studied,and the corresponding fuel-optimal conditions are obtained.Numerical simulation is conducted to verify and test the proposed algorithms.The results show that there is generally no different between the fuel consumptions by using the two different approaching modes for V-bar case.However,the conclusion for Rbar case is different that the using of continuous low-thrust cost more fuel and transfer time.
基金supported in part by the Natural Science Foundation of China(11802119)Science and Technology on Aerospace Flight Dynamics Laboratory(6142210200306)Foundation of Science and Technology on Space Intelligent Control Laboratory(6142208200303)。
文摘As to solve the collaborative relative navigation problem for near-circular orbiting small satellites in close-range under GNSS denied environment,a novel consensus constrained relative navigation algorithm based on the lever arm effect of the sensor offset from the spacecraft center of mass is proposed.Firstly,the orbital propagation model for the relative motion of multi-spacecraft is established based on Hill-Clohessy-Wiltshire dynamics and the line-of-sight measurement under sensor offset condition is modeled in Local Vertical Local Horizontal frame.Secondly,the consensus constraint model for the relative orbit state is constructed by introducing the geometry constraint between the spacecraft,based on which the consensus unscented Kalman filter is designed.Thirdly,the observability analysis is done and the necessary conditions of the sensor offset to make the state observable are obtained.Lastly,digital simulations are conducted to verify the proposed algorithm,where the comparison to the unconstrained case is also done.The results show that the estimated error of the relative position converges very quickly,the location error is smaller than 10m under the condition of 10−3 rad level camera and 5m offset.
