Aiming at the problem of relative navigation for non-cooperative rendezvous of spacecraft,this paper proposes a new angles-only navigation architecture using non-linear dynamics method. This method does not solve the ...Aiming at the problem of relative navigation for non-cooperative rendezvous of spacecraft,this paper proposes a new angles-only navigation architecture using non-linear dynamics method. This method does not solve the problem of poor observability of angles-only navigation through orbital or attitude maneuvering,but improves the observability of angles-only navigation through capturing the non-linearity of the system in the evolution of relative motion. First,three relative dynamics models and their corresponding line-of-sight(LoS)measurement equations are introduced,including the rectilinear state relative dynamics model,the curvilinear state relative dynamics model,and the relative orbital elements(ROE)state relative dynamics model. Then,an observability analysis theory based on the Gramian matrix is introduced to determine which relative dynamics model could maximize the observability of angles-only navigation. Next,an adaptive extended Kalman filtering scheme is proposed to solve the problem that the angles-only navigation filter using the non-linear dynamics method is sensitive to measurement noises. Finally,the performances of the proposed angles-only navigation architecture are tested by means of numerical simulations,which demonstrates that the angles-only navigation filtering scheme without orbital or attitude maneuvering is completely feasible through improving the modeling of the relative dynamics and LoS measurement equations.展开更多
China-Africa corporate advertising is emerging as an example of the corporate advertising genre in response to the specific rhetorical context of China-Africa win-win cooperation.Drawing on Bhatia’s Critical Genre An...China-Africa corporate advertising is emerging as an example of the corporate advertising genre in response to the specific rhetorical context of China-Africa win-win cooperation.Drawing on Bhatia’s Critical Genre Analysis(2017),this study explores the text-internal and text-external generic features of China-Africa corporate advertising by analyzing 50 collected samples.The analysis of text-internal prominence shows that China-Africa corporate advertising is unique in its frequent use of win-win-oriented and sector-dependent technical lexicons to indicate the promotional intent.It is also found that move structures vary across different sub-types of ChinaAfrica corporate advertising.Text-externally,the findings reveal a mixture of different discourses within the discursive space of China-Africa corporate advertising.In addition,the results suggest that Chinese companies invest more rhetorical efforts in enhancing the China-Africa community than African counterparts who tend to perceive China-Africa cooperation as the main avenue to attract worldwide partnerships.The findings have some practical implications for discourse construction in the Belt and Road Initiative context and shed light on the evolving nature of advertising discourse,particularly in the China-Africa win-win business context.展开更多
基金supported by the China Aerospace Science and Technology Corporation Eighth Research Institute Industry-University-Research Cooperation Fund(No.SAST 2020-019)。
文摘Aiming at the problem of relative navigation for non-cooperative rendezvous of spacecraft,this paper proposes a new angles-only navigation architecture using non-linear dynamics method. This method does not solve the problem of poor observability of angles-only navigation through orbital or attitude maneuvering,but improves the observability of angles-only navigation through capturing the non-linearity of the system in the evolution of relative motion. First,three relative dynamics models and their corresponding line-of-sight(LoS)measurement equations are introduced,including the rectilinear state relative dynamics model,the curvilinear state relative dynamics model,and the relative orbital elements(ROE)state relative dynamics model. Then,an observability analysis theory based on the Gramian matrix is introduced to determine which relative dynamics model could maximize the observability of angles-only navigation. Next,an adaptive extended Kalman filtering scheme is proposed to solve the problem that the angles-only navigation filter using the non-linear dynamics method is sensitive to measurement noises. Finally,the performances of the proposed angles-only navigation architecture are tested by means of numerical simulations,which demonstrates that the angles-only navigation filtering scheme without orbital or attitude maneuvering is completely feasible through improving the modeling of the relative dynamics and LoS measurement equations.
基金the research output of the National Social Sciences research project entitled“A Genre-based Study of the Dynamic Intertextual and Interdiscursive System in Chinese and Foreign Professional Discourse”(NO.17BYY033)。
文摘China-Africa corporate advertising is emerging as an example of the corporate advertising genre in response to the specific rhetorical context of China-Africa win-win cooperation.Drawing on Bhatia’s Critical Genre Analysis(2017),this study explores the text-internal and text-external generic features of China-Africa corporate advertising by analyzing 50 collected samples.The analysis of text-internal prominence shows that China-Africa corporate advertising is unique in its frequent use of win-win-oriented and sector-dependent technical lexicons to indicate the promotional intent.It is also found that move structures vary across different sub-types of ChinaAfrica corporate advertising.Text-externally,the findings reveal a mixture of different discourses within the discursive space of China-Africa corporate advertising.In addition,the results suggest that Chinese companies invest more rhetorical efforts in enhancing the China-Africa community than African counterparts who tend to perceive China-Africa cooperation as the main avenue to attract worldwide partnerships.The findings have some practical implications for discourse construction in the Belt and Road Initiative context and shed light on the evolving nature of advertising discourse,particularly in the China-Africa win-win business context.
