A deep space multi-file delivery protocol(DSMDP)based on LT codes is proposed to reduce the influence of long delay and a high bit error rate(BER)in deep space communication.The protocol increases sending redundancy b...A deep space multi-file delivery protocol(DSMDP)based on LT codes is proposed to reduce the influence of long delay and a high bit error rate(BER)in deep space communication.The protocol increases sending redundancy by LT codes to improve the success rate of file delivery,and adopts different protective strategies for different situations of packet loss.At the same time,the multi-file united delivery strategy is adopted to make full use of the retransmission time to reduce the end-toend transmission delay.Furthermore,the protocol determines the quantity of encoded packets according to the feedback for controlling redundancy.The simulation results show that the proposed protocol can significantly reduce the transmission delay of files,which would be effectively suitable for deep space communication environment of high BER and long delay.展开更多
The execution process of satellite-ground clock synchronization and ephemeris uploading in the system is analyzed,as well as their characterized operation and their relationship.Based on the analysis of the scheduling...The execution process of satellite-ground clock synchronization and ephemeris uploading in the system is analyzed,as well as their characterized operation and their relationship.Based on the analysis of the scheduling goal and constraint character,a heuristics rule-based multi-stage link scheduling algorithm was put forward.The algorithm distinguishes the on-off-frontier satellites from the others and schedules them by turns.The paper presented the main flow as well as the detailed design of the rule.Finally based on the current COMPASS global system,some typical resources and constraints are selected to generate an instance.Then the comparison analysis between the heuristics scheduling algorithm and three other traditional scheduling strategies are carried out.The result shows the validity and reasonability of the multi-stage strategy.展开更多
This article firstly described the related definition and technology of Ajax. Combined with Freemarker template engine with Spring and Hibernate framework technology to generate a page view, put forward the FSH the fr...This article firstly described the related definition and technology of Ajax. Combined with Freemarker template engine with Spring and Hibernate framework technology to generate a page view, put forward the FSH the framework of a complete program, and realize upload with progress bar display.展开更多
REMEMBER the days when people used to have a phone, a computer and a camera？ I do - simply because it wasn＇t that long ago. However, as technology hurtles along at the speed of light, it might have escaped some peo...REMEMBER the days when people used to have a phone, a computer and a camera？ I do - simply because it wasn＇t that long ago. However, as technology hurtles along at the speed of light, it might have escaped some people＇s attention that all these three devices now come together in the form of a smartphone, There＇s no need to carry all three devices when visiting a tourist site or monument - your handy smartphone can take a picture, log on to the Internet to post your picture on social media, and then use the calling function to tell your friends about the pictures you＇ve just posted.展开更多
基金supported by the National Natural Science Foundation of China(61271261)the Natural Science Foundation Project of CQ CSTC(CSTC2012jjA40048)
文摘A deep space multi-file delivery protocol(DSMDP)based on LT codes is proposed to reduce the influence of long delay and a high bit error rate(BER)in deep space communication.The protocol increases sending redundancy by LT codes to improve the success rate of file delivery,and adopts different protective strategies for different situations of packet loss.At the same time,the multi-file united delivery strategy is adopted to make full use of the retransmission time to reduce the end-toend transmission delay.Furthermore,the protocol determines the quantity of encoded packets according to the feedback for controlling redundancy.The simulation results show that the proposed protocol can significantly reduce the transmission delay of files,which would be effectively suitable for deep space communication environment of high BER and long delay.
基金National Natural Science Foundations of China(Nos.71201171,71501179)
文摘The execution process of satellite-ground clock synchronization and ephemeris uploading in the system is analyzed,as well as their characterized operation and their relationship.Based on the analysis of the scheduling goal and constraint character,a heuristics rule-based multi-stage link scheduling algorithm was put forward.The algorithm distinguishes the on-off-frontier satellites from the others and schedules them by turns.The paper presented the main flow as well as the detailed design of the rule.Finally based on the current COMPASS global system,some typical resources and constraints are selected to generate an instance.Then the comparison analysis between the heuristics scheduling algorithm and three other traditional scheduling strategies are carried out.The result shows the validity and reasonability of the multi-stage strategy.
文摘This article firstly described the related definition and technology of Ajax. Combined with Freemarker template engine with Spring and Hibernate framework technology to generate a page view, put forward the FSH the framework of a complete program, and realize upload with progress bar display.
文摘REMEMBER the days when people used to have a phone, a computer and a camera？ I do - simply because it wasn＇t that long ago. However, as technology hurtles along at the speed of light, it might have escaped some people＇s attention that all these three devices now come together in the form of a smartphone, There＇s no need to carry all three devices when visiting a tourist site or monument - your handy smartphone can take a picture, log on to the Internet to post your picture on social media, and then use the calling function to tell your friends about the pictures you＇ve just posted.
