A robust attitude control methodology is proposed for satellite system with double rotary payloads. The dynamic model is built by the Newton-Euler method and then the dynamic interconneetion between satellite＇s main ...A robust attitude control methodology is proposed for satellite system with double rotary payloads. The dynamic model is built by the Newton-Euler method and then the dynamic interconneetion between satellite＇s main body and payloads is described precisely. A nonlinear disturbance observer is designed for satellite＇s main body to estimate disturbance torque acted by motion of payloads. Meanwhile, the adaptive fast nonsingular terminal sliding-mode attitude stabilization controller is proposed for satellite＇s main body to quicken convergence speed of state variables. Similarly, the adaptive fast nonsingular terminal sliding-mode attitude maneuver controller is designed for each payload to weaken the disturbance effect of motion of satellite＇s main body. Simulation results verify the effectiveness of the proposed method.展开更多
Using four satellite data sets(TOMS/SBUV, OMI, MLS, and HALOE), we analyze the seasonal variations of the total column ozone(TCO) and its zonal deviation(TCO*), and reveal the vertical structure of the Ozone Low(OV) o...Using four satellite data sets(TOMS/SBUV, OMI, MLS, and HALOE), we analyze the seasonal variations of the total column ozone(TCO) and its zonal deviation(TCO*), and reveal the vertical structure of the Ozone Low(OV) over the Asian continent. Our principal findings are:(1) The TCO over the Asian continent reaches its maximum in the spring and its minimum in the autumn. The Ozone Low exists from May to September.(2) The Ozone Low has two negative cores, located in the lower and the upper stratosphere. The lower core is near 30 hPa in the winter and 70 hPa in the other seasons. The upper core varies from 10 hPa to 1 hPa among the four seasons.(3)The position of the Ozone Low in the lower and the upper stratosphere over the Asian continent shows seasonal variability.展开更多
As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network （DLSN） with MEO satellites and LEO satellites is proposed. The Inter-Orb...As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network （DLSN） with MEO satellites and LEO satellites is proposed. The Inter-Orbit-Links （IOLs） between layers is an essential factor, which affects the performances of the DLSN systems. Considering certain constellation parameters, the geometric characteristics of IOLs are described and the connectivity of MEO satellites and LEO satellites in the DLSN is analyzed. By computer simulation, the results show that IOLs should be selectively established according to certain parameters rather than the simple in-sight principle.展开更多
一个图H称为一个双星(Doub le Star),当H由2个不交的星K1,m1,K1,m2加上连接它们最大度点的一条边所构成.图G的一个支撑子图F称为一个双星(DS)因子,当F的每一个连通分支是一个双星.本文研究完全偶图Km,n的DS-因子计数,给出了Km,n的DS-因...一个图H称为一个双星(Doub le Star),当H由2个不交的星K1,m1,K1,m2加上连接它们最大度点的一条边所构成.图G的一个支撑子图F称为一个双星(DS)因子,当F的每一个连通分支是一个双星.本文研究完全偶图Km,n的DS-因子计数,给出了Km,n的DS-因子计数公式.展开更多
基金supported by the National Natural Science Foundation of China(No.91016017)the Funding of Jiangsu Innovation Program for Graduate Education (No. CXZZ12_0160)+1 种基金the Natural Science Foundation of Jiangsu Province of China(No.BK20130234)the Changzhou Sci.& Tech.Program (CE20145056)
文摘A robust attitude control methodology is proposed for satellite system with double rotary payloads. The dynamic model is built by the Newton-Euler method and then the dynamic interconneetion between satellite＇s main body and payloads is described precisely. A nonlinear disturbance observer is designed for satellite＇s main body to estimate disturbance torque acted by motion of payloads. Meanwhile, the adaptive fast nonsingular terminal sliding-mode attitude stabilization controller is proposed for satellite＇s main body to quicken convergence speed of state variables. Similarly, the adaptive fast nonsingular terminal sliding-mode attitude maneuver controller is designed for each payload to weaken the disturbance effect of motion of satellite＇s main body. Simulation results verify the effectiveness of the proposed method.
基金funded by the National Science Foundation of China (91537213, 91837311, 41675039, 41875048)
文摘Using four satellite data sets(TOMS/SBUV, OMI, MLS, and HALOE), we analyze the seasonal variations of the total column ozone(TCO) and its zonal deviation(TCO*), and reveal the vertical structure of the Ozone Low(OV) over the Asian continent. Our principal findings are:(1) The TCO over the Asian continent reaches its maximum in the spring and its minimum in the autumn. The Ozone Low exists from May to September.(2) The Ozone Low has two negative cores, located in the lower and the upper stratosphere. The lower core is near 30 hPa in the winter and 70 hPa in the other seasons. The upper core varies from 10 hPa to 1 hPa among the four seasons.(3)The position of the Ozone Low in the lower and the upper stratosphere over the Asian continent shows seasonal variability.
基金National Natural Science Foundation of China(60532030)
文摘As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network （DLSN） with MEO satellites and LEO satellites is proposed. The Inter-Orbit-Links （IOLs） between layers is an essential factor, which affects the performances of the DLSN systems. Considering certain constellation parameters, the geometric characteristics of IOLs are described and the connectivity of MEO satellites and LEO satellites in the DLSN is analyzed. By computer simulation, the results show that IOLs should be selectively established according to certain parameters rather than the simple in-sight principle.
