The concept of the separation of service,control,bearer and access in the Next Generation Network (NGN) provides a unified architecture for the network convergence in the future. Network convergence involves service,c...The concept of the separation of service,control,bearer and access in the Next Generation Network (NGN) provides a unified architecture for the network convergence in the future. Network convergence involves service,core network,access network,terminal,and operation and maintenance convergence. In the future,the converged network’s trend is to use IP Multimedia Subsystem (IMS) at the core control layer; Internet Protocol/Multiple Protocol Label Switching (IP/MPLS) technology at the core bearer layer; unified and open service provisioning architecture at the service layer; as well as support fixed,mobile,narrowband and broadband access technologies and so on at the access layer. Terminals will evolve to be multi-modular and intelligent,and would finally enable users to access full services anytime and anywhere using one number,one terminal,one account and one core network.展开更多
The technological development status of new generation low cost small-lift launch vehicles applied to small satellite launch is investigated in this paper. The development trends are summarized, including low cost and...The technological development status of new generation low cost small-lift launch vehicles applied to small satellite launch is investigated in this paper. The development trends are summarized, including low cost and rapid response capability, utilization of mature rocket and missile technology, the development of mobile launch technology adopting air-based platforms and use of innovative technology. Moreover, the external power and internal demand of the small-lift launch vehicle are analyzed and the market prospect is forecasted. Finally, proposals for the development of small-lift launch vehicles are put forward, including exploration of the potential of existing rocket and missile technology, development of multi-platform mobile launch technology and further application of innovative technology and ideas.展开更多
Landscape preference(LP)studies highlight one of the most important issues of human-environment relationship,and their related publications have increased rapidly over the last two decades.However,there is no systemat...Landscape preference(LP)studies highlight one of the most important issues of human-environment relationship,and their related publications have increased rapidly over the last two decades.However,there is no systematic review with a holistic understanding of this field.here we applied a bibliometric approach to examine the evolution of LP research and identify its status and future prospects.We obtained 7,637 LP research publications from Web of Science core collection from 1968 to 2019 and analyzed the characteristics of publication outputs as well as performances in various countries and institutions.Besides,content keywords analysis was conducted to discover the drivers,focus,motivation,and trends of LP research.We found that 1)publications,subject categories,and active journals increased rapidly since the 2000s;2)the USA,England,and Australia are the leading countries in LP research,while China is starting to have some influence;3)LP research is most closely linked to ecological and environmental studies,being developed by objective drivers,i.e.,interactions with landscape change,and subjective motivations;and 4)LP research is advancing the landscape sustainability science,integrating natural and social science together through ecosystem services.By comprehensively reviewing the evolution and prospect of LP research,we provide insights for further research in this field.展开更多
文摘The concept of the separation of service,control,bearer and access in the Next Generation Network (NGN) provides a unified architecture for the network convergence in the future. Network convergence involves service,core network,access network,terminal,and operation and maintenance convergence. In the future,the converged network’s trend is to use IP Multimedia Subsystem (IMS) at the core control layer; Internet Protocol/Multiple Protocol Label Switching (IP/MPLS) technology at the core bearer layer; unified and open service provisioning architecture at the service layer; as well as support fixed,mobile,narrowband and broadband access technologies and so on at the access layer. Terminals will evolve to be multi-modular and intelligent,and would finally enable users to access full services anytime and anywhere using one number,one terminal,one account and one core network.
文摘The technological development status of new generation low cost small-lift launch vehicles applied to small satellite launch is investigated in this paper. The development trends are summarized, including low cost and rapid response capability, utilization of mature rocket and missile technology, the development of mobile launch technology adopting air-based platforms and use of innovative technology. Moreover, the external power and internal demand of the small-lift launch vehicle are analyzed and the market prospect is forecasted. Finally, proposals for the development of small-lift launch vehicles are put forward, including exploration of the potential of existing rocket and missile technology, development of multi-platform mobile launch technology and further application of innovative technology and ideas.
基金This work was supported by Shanghai Municipal Committee of Science and Technology[21ZR1408500]the Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration[SHUES2021A02]。
文摘Landscape preference(LP)studies highlight one of the most important issues of human-environment relationship,and their related publications have increased rapidly over the last two decades.However,there is no systematic review with a holistic understanding of this field.here we applied a bibliometric approach to examine the evolution of LP research and identify its status and future prospects.We obtained 7,637 LP research publications from Web of Science core collection from 1968 to 2019 and analyzed the characteristics of publication outputs as well as performances in various countries and institutions.Besides,content keywords analysis was conducted to discover the drivers,focus,motivation,and trends of LP research.We found that 1)publications,subject categories,and active journals increased rapidly since the 2000s;2)the USA,England,and Australia are the leading countries in LP research,while China is starting to have some influence;3)LP research is most closely linked to ecological and environmental studies,being developed by objective drivers,i.e.,interactions with landscape change,and subjective motivations;and 4)LP research is advancing the landscape sustainability science,integrating natural and social science together through ecosystem services.By comprehensively reviewing the evolution and prospect of LP research,we provide insights for further research in this field.
