In this paper a new idea, based on discussing the essence of flutter, to investigate flutter problems is proposed that we only study a few modes of an aeroelastic system instead of studying the whole. In the light of ...In this paper a new idea, based on discussing the essence of flutter, to investigate flutter problems is proposed that we only study a few modes of an aeroelastic system instead of studying the whole. In the light of this, an approach to analysing flutter characteristics which combines the merit of graphic and analytic methods, is presented. Also an optimal cost function with clear physical meaning which can overcome some inherent drawbacks of linear quadratic technique, is developed. The paper has shown a numerical example of an elastic wing, in which some comparisons between the approach and 'V-G' method for calculating the critical point (Vf,wf ) are carried out as well.展开更多
Bistatic forward-looking synthetic aperture radar（SAR） has many advantages and applications owing to its twodimensional imaging capability.There could be various imaging configurations because of the geometric flexi...Bistatic forward-looking synthetic aperture radar（SAR） has many advantages and applications owing to its twodimensional imaging capability.There could be various imaging configurations because of the geometric flexibility of bistatic platforms,resulting in kinds of models built independently among which there could be some similar even the same motion features.Comprehensive research on such systems in a more comprehensive and general point of view is required to address their difference and consistency.Property analysis of bistatic forwardlooking SAR with arbitrary geometry is achieved including stripmap and spotlight modes on airborne platform,missile-borne platform,and hybrid platform of both.Emphasis is placed on azimuth space variance of some key parameters significantly affecting the subsequent imaging processing,based on which the frequency spectra are further described and compared considering respective features of different platforms for frequency imaging algorithm developing.Simulation results confirm the effectiveness and correctness of our analysis.展开更多
文摘In this paper a new idea, based on discussing the essence of flutter, to investigate flutter problems is proposed that we only study a few modes of an aeroelastic system instead of studying the whole. In the light of this, an approach to analysing flutter characteristics which combines the merit of graphic and analytic methods, is presented. Also an optimal cost function with clear physical meaning which can overcome some inherent drawbacks of linear quadratic technique, is developed. The paper has shown a numerical example of an elastic wing, in which some comparisons between the approach and 'V-G' method for calculating the critical point (Vf,wf ) are carried out as well.
基金supported by the National Natural Science Foundation of China(6100121161303035+1 种基金61471283)the Fundamental Research Funds for the Central Universities(K5051202016)
文摘Bistatic forward-looking synthetic aperture radar（SAR） has many advantages and applications owing to its twodimensional imaging capability.There could be various imaging configurations because of the geometric flexibility of bistatic platforms,resulting in kinds of models built independently among which there could be some similar even the same motion features.Comprehensive research on such systems in a more comprehensive and general point of view is required to address their difference and consistency.Property analysis of bistatic forwardlooking SAR with arbitrary geometry is achieved including stripmap and spotlight modes on airborne platform,missile-borne platform,and hybrid platform of both.Emphasis is placed on azimuth space variance of some key parameters significantly affecting the subsequent imaging processing,based on which the frequency spectra are further described and compared considering respective features of different platforms for frequency imaging algorithm developing.Simulation results confirm the effectiveness and correctness of our analysis.
