This paper presents flight results and lessons learned from the Spaceborne Autonomous Formation Flying Experiment （SAFE） conducted by the German Space Operations Center in the frame of the Swedish PRISMA technology ...This paper presents flight results and lessons learned from the Spaceborne Autonomous Formation Flying Experiment （SAFE） conducted by the German Space Operations Center in the frame of the Swedish PRISMA technology demonstration mission. PR1SMA involves two fully autonomous formation-flying spacecraft which have been launched in June 2010 in a dawn/dusk orbit at an altitude of 750 km. SAFE represents one of the first demonstrations in low Earth orbit of an advanced guidance, navigation and control system for dual-spacecraft formations. Innovative techniques based on carrier-phase differential GPS （Global Positioning System）, relative eccentricity/inclination vectors and impulsive maneuvering are validated and tuned in orbit to achieve centimeter accurate real-time relative navigation, reliable formation keeping at the meter level and flexible formation reconfiguration capabilities. The technologies demonstrated within SAFE are considered as key precursors of future distributed satellite systems for unrivaled remote sensing and space exploration.展开更多
Consider a four-dimensional system having a two-dimensional invariant surface. By analyzing the solutions of bifurcation equations, this paper studied the bifurcation phenomena of a k multiple closed orbit in the inva...Consider a four-dimensional system having a two-dimensional invariant surface. By analyzing the solutions of bifurcation equations, this paper studied the bifurcation phenomena of a k multiple closed orbit in the invariant surface. Sufficient conditions for the existence of periodic orbits generated by the k multiple closed orbit were given.展开更多
In this paper,it is shown that the homoclinic orbits exist in iterated functional systems.so do the solitary wave structures.Moreover,Harr father wavelet,Mexican Cap wavelet,and other closed form wavelets have this so...In this paper,it is shown that the homoclinic orbits exist in iterated functional systems.so do the solitary wave structures.Moreover,Harr father wavelet,Mexican Cap wavelet,and other closed form wavelets have this solitary wave structure,too So wavelet is a certain kind of solitary wave.展开更多
Consider a three-dimensional system having an invariant surface. By using bifurca- tion techniques and analyzing the solutions of bifurcation equations, the authors study the spacial bifurcation phenomena of a k multi...Consider a three-dimensional system having an invariant surface. By using bifurca- tion techniques and analyzing the solutions of bifurcation equations, the authors study the spacial bifurcation phenomena of a k multiple closed orbit in the invariant surface. The su?cient conditions of the existence of many closed orbits bifurcate from the k multiple closed orbit are obtained.展开更多
Bifurcations of periodic orbits of three-well Duffing system with a phase shift are investigated in detail. The conditions of the existence and bifurcations for harmonics, subharmonics （2-order, 3- order and m-order...Bifurcations of periodic orbits of three-well Duffing system with a phase shift are investigated in detail. The conditions of the existence and bifurcations for harmonics, subharmonics （2-order, 3- order and m-order） and superharmonics under small perturbations are given by using second-order averaging method and Melnikov＇s method. The influence of the phase shift on the dynamics is also obtained.展开更多
An analytical model is presented to study vertical dynamic response of the ballastless track on long-span plate-truss cable-stayed bridges based on an explicit dynamic analysis method.In the model,the train,ballastles...An analytical model is presented to study vertical dynamic response of the ballastless track on long-span plate-truss cable-stayed bridges based on an explicit dynamic analysis method.In the model,the train,ballastless track and bridge are treated as a coupled vibration system with interaction.By simulating the dynamic process of the system,this paper discusses the distribution law of dynamic responses of the bridge deck and the bed slab.It shows the necessity of a base plate for the ballastless track on the long-span plate-truss cable-stayed bridge.Comparison of the influence of different train speeds and stiffness of the elastic vibration-damping pad on the dynamic responses of the bridge deck and the bed slab is also made.The reasonable stiffness value of elastic vibration-damping pad is proposed.展开更多
A high-codimension homoclinic bifurcation is considered with one orbit flip and two inclination flips accompanied by resonant principal eigenvalues. A local active coordinate system in a small neighborhood of homoclin...A high-codimension homoclinic bifurcation is considered with one orbit flip and two inclination flips accompanied by resonant principal eigenvalues. A local active coordinate system in a small neighborhood of homoclinic orbit is introduced. By analysis of the bifurcation equation, the authors obtain the conditions when the original flip homoclinic orbit is kept or broken. The existence and the existence regions of several double periodic orbits and one triple periodic orbit bifurcations are proved. Moreover, the complicated homoclinic-doubling bifurcations are found and expressed approximately.展开更多
文摘This paper presents flight results and lessons learned from the Spaceborne Autonomous Formation Flying Experiment （SAFE） conducted by the German Space Operations Center in the frame of the Swedish PRISMA technology demonstration mission. PR1SMA involves two fully autonomous formation-flying spacecraft which have been launched in June 2010 in a dawn/dusk orbit at an altitude of 750 km. SAFE represents one of the first demonstrations in low Earth orbit of an advanced guidance, navigation and control system for dual-spacecraft formations. Innovative techniques based on carrier-phase differential GPS （Global Positioning System）, relative eccentricity/inclination vectors and impulsive maneuvering are validated and tuned in orbit to achieve centimeter accurate real-time relative navigation, reliable formation keeping at the meter level and flexible formation reconfiguration capabilities. The technologies demonstrated within SAFE are considered as key precursors of future distributed satellite systems for unrivaled remote sensing and space exploration.
文摘Consider a four-dimensional system having a two-dimensional invariant surface. By analyzing the solutions of bifurcation equations, this paper studied the bifurcation phenomena of a k multiple closed orbit in the invariant surface. Sufficient conditions for the existence of periodic orbits generated by the k multiple closed orbit were given.
基金The project supported by National Natural Science Foundation of China under Grant Nos.40045016 and No.40175016
文摘In this paper,it is shown that the homoclinic orbits exist in iterated functional systems.so do the solitary wave structures.Moreover,Harr father wavelet,Mexican Cap wavelet,and other closed form wavelets have this solitary wave structure,too So wavelet is a certain kind of solitary wave.
基金Project supported by the Ministry of Education of China (No.20010248019, No.20020248010) and theNational Natural Science Foundation of China (No.10371072).
文摘Consider a three-dimensional system having an invariant surface. By using bifurca- tion techniques and analyzing the solutions of bifurcation equations, the authors study the spacial bifurcation phenomena of a k multiple closed orbit in the invariant surface. The su?cient conditions of the existence of many closed orbits bifurcate from the k multiple closed orbit are obtained.
基金supported by the National Natural Science Foundation of China under Grant No.10726022CCNU Project under Grant No.CCNU09A01003Tianjin Fund for Natural Sciences "07JCYBJC14700"
文摘Bifurcations of periodic orbits of three-well Duffing system with a phase shift are investigated in detail. The conditions of the existence and bifurcations for harmonics, subharmonics （2-order, 3- order and m-order） and superharmonics under small perturbations are given by using second-order averaging method and Melnikov＇s method. The influence of the phase shift on the dynamics is also obtained.
基金supported by the National Natural Science Foundation of China(Grant No.NNSF-U1334201)the National Basic Research Program of China("973"Project)(Grant No.2013CB036206)the Sichuan Province Youth Science and Technology Innovation Team(Grant No.2015TD0004)
文摘An analytical model is presented to study vertical dynamic response of the ballastless track on long-span plate-truss cable-stayed bridges based on an explicit dynamic analysis method.In the model,the train,ballastless track and bridge are treated as a coupled vibration system with interaction.By simulating the dynamic process of the system,this paper discusses the distribution law of dynamic responses of the bridge deck and the bed slab.It shows the necessity of a base plate for the ballastless track on the long-span plate-truss cable-stayed bridge.Comparison of the influence of different train speeds and stiffness of the elastic vibration-damping pad on the dynamic responses of the bridge deck and the bed slab is also made.The reasonable stiffness value of elastic vibration-damping pad is proposed.
基金supported by the National Natural Science Foundation of China(No.11126097)
文摘A high-codimension homoclinic bifurcation is considered with one orbit flip and two inclination flips accompanied by resonant principal eigenvalues. A local active coordinate system in a small neighborhood of homoclinic orbit is introduced. By analysis of the bifurcation equation, the authors obtain the conditions when the original flip homoclinic orbit is kept or broken. The existence and the existence regions of several double periodic orbits and one triple periodic orbit bifurcations are proved. Moreover, the complicated homoclinic-doubling bifurcations are found and expressed approximately.
