Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to moni...Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L4 and L5 and the collinear point L3 of the CRTBP （circular restricted three-body problem） in the Sun-Earth system. These trajectories could serve as channels through where material can be transported from L5 to L3 by performing small maneuvers at the departure of the Trojan orbit. The size of these maneuvers at L5 is between 299 m/s and 730 m/s depending on the transfer time of the trajectory and does not need any deterministic maneuvers at L3. Our results suggest that material may also be transported from the Trojan orbits to quasi-satellite orbits or even displaced quasi-satellite orbits.展开更多
There has been increasing research in developing offline web applications. This paper concentrates on developing a new methodology for the online assessment web applications that could be used while offline. It is imp...There has been increasing research in developing offline web applications. This paper concentrates on developing a new methodology for the online assessment web applications that could be used while offline. It is important to retrieve the critical data collected during an examination without a provision of a backup mechanism. There is a need for an assessment system that can adapt to work uninterruptedly and without loss of critical data while there is intermittent intemet discontinuity. This paper describes architecture and implementation of online assessment system with offline capabilities. Online assessment system with offline capabilities will not interrupt examinee＇s experience while appearing for an assessment test if intemet connection is not available. A development methodology is designed and a compliant framework is implemented to enhance online assessment system with offline capabilities.展开更多
文摘Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L4 and L5 and the collinear point L3 of the CRTBP （circular restricted three-body problem） in the Sun-Earth system. These trajectories could serve as channels through where material can be transported from L5 to L3 by performing small maneuvers at the departure of the Trojan orbit. The size of these maneuvers at L5 is between 299 m/s and 730 m/s depending on the transfer time of the trajectory and does not need any deterministic maneuvers at L3. Our results suggest that material may also be transported from the Trojan orbits to quasi-satellite orbits or even displaced quasi-satellite orbits.
文摘There has been increasing research in developing offline web applications. This paper concentrates on developing a new methodology for the online assessment web applications that could be used while offline. It is important to retrieve the critical data collected during an examination without a provision of a backup mechanism. There is a need for an assessment system that can adapt to work uninterruptedly and without loss of critical data while there is intermittent intemet discontinuity. This paper describes architecture and implementation of online assessment system with offline capabilities. Online assessment system with offline capabilities will not interrupt examinee＇s experience while appearing for an assessment test if intemet connection is not available. A development methodology is designed and a compliant framework is implemented to enhance online assessment system with offline capabilities.
