Dear Readers:Antarctica,with its unparalleled atmospheric transparency,extended polar nights,and unique geographical position,has become a premier site for modern astronomical observation.Two decades ago,the Chinese A...Dear Readers:Antarctica,with its unparalleled atmospheric transparency,extended polar nights,and unique geographical position,has become a premier site for modern astronomical observation.Two decades ago,the Chinese Antarctic Research Expedition(CHINARE)team reached Dome A,the highest point of the Antarctic ice sheet,marking the beginning of a new era for astro-nomical research from the Antarctic plateau.展开更多
In order to realize the coexistence between the LTE system and the spectrum authorized systems over 700MHz frequency band,the geographical position and operation band location between long term evolution(LTE)base stat...In order to realize the coexistence between the LTE system and the spectrum authorized systems over 700MHz frequency band,the geographical position and operation band location between long term evolution(LTE)base stations and digital tevevision transmission tower should satisfy certain constraints,which are analyzed and deduced in this paper.Under the concluded constraints,the interference to each other is lower than their interference tolerances,so that the coexistance between the two types of systems is performed.Based on the constraints for both LTE and spectrum authorized systems,numerical results of the geographical position interval and operation band location interval are obtained,which have significant practical value for the LTE base station placement,network planning and operation band selection.展开更多
The aim of the paper is to evaluate the impacts of bus lane on bus travel time reliability.The data used are the Geographic Positioning System(GPS) data of two bus lines running parallel streets in Shenzhen,China,one ...The aim of the paper is to evaluate the impacts of bus lane on bus travel time reliability.The data used are the Geographic Positioning System(GPS) data of two bus lines running parallel streets in Shenzhen,China,one of which is a bus lane and the other is a regular lane.Two linear regression models are developed to evaluate the influence of bus lane which has a separated right of way.Other factors including running direction,day of week,time of day,dwell time,and delay at the start point are also considered in the model.Without published time tables,coefficient of variance(CV) of travel time is employed to explore the impacts of bus lane.The results indicate that bus lane can save 22.0% of travel time,reduce 11.5% of the CV of travel time,and decrease the variance of headway by 17.4%.The analysis on bus travel time reliability could help operators and drivers improve the quality of transit service.It also sheds light on how to assess the effectiveness of bus lane for transit planners and service operators.展开更多
Nagqu,located in the Xizang Autonomous Region,has an average altitude of over 4,500 meters,with oxygen levels in summer at only 58 percent of that at sea level.The city holds a unique geographical position as Xizang’...Nagqu,located in the Xizang Autonomous Region,has an average altitude of over 4,500 meters,with oxygen levels in summer at only 58 percent of that at sea level.The city holds a unique geographical position as Xizang’s"Northern Gate".Nagqu is rich in resources,such as livestock,water,wind,solar energy,Tibetan medicine,and tourism sectors,offering vast development prospects.展开更多
According to local chronicles,the name i“Shanghai”originates from its geographical position“on the upper reaches of the sea.”However,this interpretation is merely a literal guess based on the characters“Shang”(m...According to local chronicles,the name i“Shanghai”originates from its geographical position“on the upper reaches of the sea.”However,this interpretation is merely a literal guess based on the characters“Shang”(meaning“upper”)and“Hai”(meaning“sea”).The origin of a place's name usually has a more specific reason.In fact,Shanghai got its name because it emerged along a small river called“Shanghai Pu.”展开更多
This paper presents a novel distributed media access control(MAC)address assignment algorithm,namely virtual grid spatial reusing(VGSR),for wireless sensor networks,which reduces the size of the MAC address efficientl...This paper presents a novel distributed media access control(MAC)address assignment algorithm,namely virtual grid spatial reusing(VGSR),for wireless sensor networks,which reduces the size of the MAC address efficiently on the basis of both the spatial reuse of MAC address and the mapping of geographical position.By adjusting the communication range of sensor nodes,VGSR algorithm can minimize the size of MAC address and meanwhile guarantee the connectivity of the sensor network.Theoretical analysis and experimental results show that VGSR algorithm is not only of low energy cost,but also scales well with the network size,with its performance superior to that of other existing algorithms.展开更多
Situated in a unique geographical position with respect to the China-proposed Belt and Road Initiative, Nepal expects to gain momentum for its development by taking part in the regional development blueprint.
文摘Dear Readers:Antarctica,with its unparalleled atmospheric transparency,extended polar nights,and unique geographical position,has become a premier site for modern astronomical observation.Two decades ago,the Chinese Antarctic Research Expedition(CHINARE)team reached Dome A,the highest point of the Antarctic ice sheet,marking the beginning of a new era for astro-nomical research from the Antarctic plateau.
基金Supported by the National High Technology Research and Development Program of China(No.2011AA01A105)the Key Deplogment Project of China Academic of Sciences(KGZD-EW-103)Shanghai Committee of Science and Technology(11DZ1500500)
文摘In order to realize the coexistence between the LTE system and the spectrum authorized systems over 700MHz frequency band,the geographical position and operation band location between long term evolution(LTE)base stations and digital tevevision transmission tower should satisfy certain constraints,which are analyzed and deduced in this paper.Under the concluded constraints,the interference to each other is lower than their interference tolerances,so that the coexistance between the two types of systems is performed.Based on the constraints for both LTE and spectrum authorized systems,numerical results of the geographical position interval and operation band location interval are obtained,which have significant practical value for the LTE base station placement,network planning and operation band selection.
文摘The aim of the paper is to evaluate the impacts of bus lane on bus travel time reliability.The data used are the Geographic Positioning System(GPS) data of two bus lines running parallel streets in Shenzhen,China,one of which is a bus lane and the other is a regular lane.Two linear regression models are developed to evaluate the influence of bus lane which has a separated right of way.Other factors including running direction,day of week,time of day,dwell time,and delay at the start point are also considered in the model.Without published time tables,coefficient of variance(CV) of travel time is employed to explore the impacts of bus lane.The results indicate that bus lane can save 22.0% of travel time,reduce 11.5% of the CV of travel time,and decrease the variance of headway by 17.4%.The analysis on bus travel time reliability could help operators and drivers improve the quality of transit service.It also sheds light on how to assess the effectiveness of bus lane for transit planners and service operators.
文摘Nagqu,located in the Xizang Autonomous Region,has an average altitude of over 4,500 meters,with oxygen levels in summer at only 58 percent of that at sea level.The city holds a unique geographical position as Xizang’s"Northern Gate".Nagqu is rich in resources,such as livestock,water,wind,solar energy,Tibetan medicine,and tourism sectors,offering vast development prospects.
文摘According to local chronicles,the name i“Shanghai”originates from its geographical position“on the upper reaches of the sea.”However,this interpretation is merely a literal guess based on the characters“Shang”(meaning“upper”)and“Hai”(meaning“sea”).The origin of a place's name usually has a more specific reason.In fact,Shanghai got its name because it emerged along a small river called“Shanghai Pu.”
基金supported by the National Natural Science Foundation of China(Grant Nos.60572146,60372048 and 60496316).
文摘This paper presents a novel distributed media access control(MAC)address assignment algorithm,namely virtual grid spatial reusing(VGSR),for wireless sensor networks,which reduces the size of the MAC address efficiently on the basis of both the spatial reuse of MAC address and the mapping of geographical position.By adjusting the communication range of sensor nodes,VGSR algorithm can minimize the size of MAC address and meanwhile guarantee the connectivity of the sensor network.Theoretical analysis and experimental results show that VGSR algorithm is not only of low energy cost,but also scales well with the network size,with its performance superior to that of other existing algorithms.
文摘Situated in a unique geographical position with respect to the China-proposed Belt and Road Initiative, Nepal expects to gain momentum for its development by taking part in the regional development blueprint.
