China's transition from a planned economy to a market economy has resulted in many changes in its urban structure and society and provided an opportunity for a quasi-longitudinal case study on the relationship bet...China's transition from a planned economy to a market economy has resulted in many changes in its urban structure and society and provided an opportunity for a quasi-longitudinal case study on the relationship between the built environment and activity-travel behavior.This paper draws upon data from an activity diary survey conducted in Beijing in 2007.The survey sample comprised 652 residents living in Danwei(work unit),commodity housing,and affordable housing neighborhoods.On the basis of the three-dimensional geo-visualization analysis of the space-time path and statistical multivariate regression models of daily travel and leisure time,it was found that both residential spatial factors and socio-demographics influence residents' daily behaviors.The findings show that Danwei residents have less daily travel time than those who live in commodity housing,but people living in affordable housing endure the longest travel time.Daily leisure time is associated more with individual attributes.We argue that although China's transition is currently gradual,the Danwei system may continue to play significant roles in daily life,and it might provide a valuable model for neighborhood spatial planning.展开更多
LM-6,China’s new generation launch vehicle,achieved a successful launch at12：50 Beijing time on November 21,2017 from the Taiyuan Satellite Launch Center.It was the first commercial launch mission of LM-6 since its ...LM-6,China’s new generation launch vehicle,achieved a successful launch at12：50 Beijing time on November 21,2017 from the Taiyuan Satellite Launch Center.It was the first commercial launch mission of LM-6 since its successful maiden flight in 2015.The LM-6carrier rocket carried 3＂Jilin-1＂video satellites into space and accurately placed them into their preset orbits.LM-6 is an important member of the nation’s family of new generation of launch vehicles.展开更多
LM-2D carrier rockets placed two land survey satellites into their preset orbits from the Jiuquan Satellite Launch Center at 12：11 Beijing time on December 3 and 12：14 Beijing time on December 23 respectively.The mi...LM-2D carrier rockets placed two land survey satellites into their preset orbits from the Jiuquan Satellite Launch Center at 12：11 Beijing time on December 3 and 12：14 Beijing time on December 23 respectively.The missions were the 257th and the 259th flights of the LM series launch vehicle respectively.The two land survey satellites were developed by DFH Satellite Co.,Ltd.under the China Academy of Space Technology（CAST）.展开更多
China launched Algeria’s communications satellite,Alcomsat-1,on a LM-3B carrier rocket into its preset orbit from the Xichang Satellite Launch Center at 00：40 Beijing time on December 11 successfully.Alcomsat-1 is A...China launched Algeria’s communications satellite,Alcomsat-1,on a LM-3B carrier rocket into its preset orbit from the Xichang Satellite Launch Center at 00：40 Beijing time on December 11 successfully.Alcomsat-1 is Algeria’s first communications satellite as well as the first cooperative project in the aerospace industry between China and Algeria.展开更多
A LM-2F launch vehicle lifted off from the Jiuquan Satellite Launch Center at22：04 Beijing time on September 15,putting China’s first space laboratory Tiangong 2 into space.575 seconds after the liftoff,Tiangong 2 s...A LM-2F launch vehicle lifted off from the Jiuquan Satellite Launch Center at22：04 Beijing time on September 15,putting China’s first space laboratory Tiangong 2 into space.575 seconds after the liftoff,Tiangong 2 separated from the carrier rocket and entered its preset orbit.The launch achieved complete success.展开更多
A LM-2D launch vehicle launched a quantum satellite along with a LX-1thin atmosphere research satellite and a Spanish small satellite from the Jiuquan Satellite Launch Center at 01：40 Beijing time on August 16.The wo...A LM-2D launch vehicle launched a quantum satellite along with a LX-1thin atmosphere research satellite and a Spanish small satellite from the Jiuquan Satellite Launch Center at 01：40 Beijing time on August 16.The world’s first quantum satellite is named Micius after a Chinese philosopher and scientist who lived 2,500 years ago.展开更多
At 7：30 Beijing time on Ocotber17,2016,a LM-2F launch vehicle soared up from the Jiuquan Satellite Launch Center,successfully putting the Shenzhou 11 spaceship and its crew into space.Two astronauts,JING Haipeng and ...At 7：30 Beijing time on Ocotber17,2016,a LM-2F launch vehicle soared up from the Jiuquan Satellite Launch Center,successfully putting the Shenzhou 11 spaceship and its crew into space.Two astronauts,JING Haipeng and CHEN Dong will carry out the 6th manned spaceflight mission of the country.展开更多
Traditional 802.11 power saving mechanism (PSM) treats multicast and broadcast traffic equally, and suffers sig-nificant performance degradation with multicast background traffic. This paper proposes an enhanced PSM t...Traditional 802.11 power saving mechanism (PSM) treats multicast and broadcast traffic equally, and suffers sig-nificant performance degradation with multicast background traffic. This paper proposes an enhanced PSM that effectively dif-ferentiates multicast streams. It re-arranges the virtual bitmap of the traffic indication map (TIM) to carry traffic status for mul-ticast groups and introduces a concept of sequential transmission of multi-addressed data to facilitate differentiation among mul-ticast groups. Our analysis shows that the enhanced PSM can effectively save power in mixed traffic environments.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.40671058,41071102)National'TwelfthFive-Year'Plan for Science and Technology Support(No.2012BAJ 05B04)
文摘China's transition from a planned economy to a market economy has resulted in many changes in its urban structure and society and provided an opportunity for a quasi-longitudinal case study on the relationship between the built environment and activity-travel behavior.This paper draws upon data from an activity diary survey conducted in Beijing in 2007.The survey sample comprised 652 residents living in Danwei(work unit),commodity housing,and affordable housing neighborhoods.On the basis of the three-dimensional geo-visualization analysis of the space-time path and statistical multivariate regression models of daily travel and leisure time,it was found that both residential spatial factors and socio-demographics influence residents' daily behaviors.The findings show that Danwei residents have less daily travel time than those who live in commodity housing,but people living in affordable housing endure the longest travel time.Daily leisure time is associated more with individual attributes.We argue that although China's transition is currently gradual,the Danwei system may continue to play significant roles in daily life,and it might provide a valuable model for neighborhood spatial planning.
文摘LM-6,China’s new generation launch vehicle,achieved a successful launch at12：50 Beijing time on November 21,2017 from the Taiyuan Satellite Launch Center.It was the first commercial launch mission of LM-6 since its successful maiden flight in 2015.The LM-6carrier rocket carried 3＂Jilin-1＂video satellites into space and accurately placed them into their preset orbits.LM-6 is an important member of the nation’s family of new generation of launch vehicles.
文摘LM-2D carrier rockets placed two land survey satellites into their preset orbits from the Jiuquan Satellite Launch Center at 12：11 Beijing time on December 3 and 12：14 Beijing time on December 23 respectively.The missions were the 257th and the 259th flights of the LM series launch vehicle respectively.The two land survey satellites were developed by DFH Satellite Co.,Ltd.under the China Academy of Space Technology（CAST）.
文摘China launched Algeria’s communications satellite,Alcomsat-1,on a LM-3B carrier rocket into its preset orbit from the Xichang Satellite Launch Center at 00：40 Beijing time on December 11 successfully.Alcomsat-1 is Algeria’s first communications satellite as well as the first cooperative project in the aerospace industry between China and Algeria.
文摘A LM-2F launch vehicle lifted off from the Jiuquan Satellite Launch Center at22：04 Beijing time on September 15,putting China’s first space laboratory Tiangong 2 into space.575 seconds after the liftoff,Tiangong 2 separated from the carrier rocket and entered its preset orbit.The launch achieved complete success.
文摘A LM-2D launch vehicle launched a quantum satellite along with a LX-1thin atmosphere research satellite and a Spanish small satellite from the Jiuquan Satellite Launch Center at 01：40 Beijing time on August 16.The world’s first quantum satellite is named Micius after a Chinese philosopher and scientist who lived 2,500 years ago.
文摘At 7：30 Beijing time on Ocotber17,2016,a LM-2F launch vehicle soared up from the Jiuquan Satellite Launch Center,successfully putting the Shenzhou 11 spaceship and its crew into space.Two astronauts,JING Haipeng and CHEN Dong will carry out the 6th manned spaceflight mission of the country.
基金Project (Nos. 60574087 and 60721003) supported by the National Natural Science Foundation of China
文摘Traditional 802.11 power saving mechanism (PSM) treats multicast and broadcast traffic equally, and suffers sig-nificant performance degradation with multicast background traffic. This paper proposes an enhanced PSM that effectively dif-ferentiates multicast streams. It re-arranges the virtual bitmap of the traffic indication map (TIM) to carry traffic status for mul-ticast groups and introduces a concept of sequential transmission of multi-addressed data to facilitate differentiation among mul-ticast groups. Our analysis shows that the enhanced PSM can effectively save power in mixed traffic environments.
