Unconventional natural gas has become an important supplement to conventional energy sources,and the process of enrichment and purification of methane from low concentration coalbed methane is crucial.To this end,we r...Unconventional natural gas has become an important supplement to conventional energy sources,and the process of enrichment and purification of methane from low concentration coalbed methane is crucial.To this end,we report a copper-based metal-organic framework(MOF),ZJNU-119Cu,featuring two methane traps constructed with uncoordinated carboxylic acid oxygens and open metal sites.ZJNU-119Cu exhibits a high methane adsorption capacity(58.2 cm^(3)·g^(-1))at 298 K and 0.1 MPa and excellent CH_(4)/N_(2) separation performance under dynamic conditions.Densityfunctional theory calculations combined with grand canonical Monte Carlo simulation theory reveal the interaction mechanism for the uncoordinated carboxylic acid oxygen atoms and open metal sites in ZJNU-119Cu with CH4.The gas adsorption isotherms,heat of adsorption calculations,and breakthrough separation experiments indicate that this MOF is a very promising adsorbent for CH_(4)/N_(2) separation.展开更多
Unsourced multiple access(UMA)is a multi-access technology for massive,low-power,uncoordinated,and unsourced Machine Type Communication(MTC)networks.It ensures transmission reliability under the premise of high energy...Unsourced multiple access(UMA)is a multi-access technology for massive,low-power,uncoordinated,and unsourced Machine Type Communication(MTC)networks.It ensures transmission reliability under the premise of high energy efficiency.Based on the analysis of the 6G MTC key performance indicators(KPIs)and scenario characteristics,this paper summarizes its requirements for radio access networks.Following this,the existing multiple access models are analyzed under these standards to determine UMA's advantages for 6G MTC according to its design characteristics.The critical technology of UMA is the design of its multiple-access coding scheme.Therefore,the existing UMA coding schemes from different coding paradigms are further summarized and compared.In particular,this paper comprehensively considers the energy efficiency and computational complexity of these schemes,studies the changes of the above two indexes with the increase of access scale,and considers the trade-off between the two.It is revealed by the above analysis that some guiding rules of UMA coding design.Finally,the open problems and potentials in this field are given for future research.展开更多
基金financial support from the National Natural Science Foundation of China(22408258 and 22378287)the Joint Founds of the National Natural Science Foundation of China(U20B6004)the Natural Science Foundation of Shanxi Province(202303021222012).
文摘Unconventional natural gas has become an important supplement to conventional energy sources,and the process of enrichment and purification of methane from low concentration coalbed methane is crucial.To this end,we report a copper-based metal-organic framework(MOF),ZJNU-119Cu,featuring two methane traps constructed with uncoordinated carboxylic acid oxygens and open metal sites.ZJNU-119Cu exhibits a high methane adsorption capacity(58.2 cm^(3)·g^(-1))at 298 K and 0.1 MPa and excellent CH_(4)/N_(2) separation performance under dynamic conditions.Densityfunctional theory calculations combined with grand canonical Monte Carlo simulation theory reveal the interaction mechanism for the uncoordinated carboxylic acid oxygen atoms and open metal sites in ZJNU-119Cu with CH4.The gas adsorption isotherms,heat of adsorption calculations,and breakthrough separation experiments indicate that this MOF is a very promising adsorbent for CH_(4)/N_(2) separation.
基金supported by National Natural Science Foundation of China under Grant 61971062,Grant 92067202,Grant 62071058,Grant 62001049Beijing Natural Science Foundation under Grant 4222012Beijing University of Posts and Telecommunications China Mobile Research Institute Joint Innovation Center。
文摘Unsourced multiple access(UMA)is a multi-access technology for massive,low-power,uncoordinated,and unsourced Machine Type Communication(MTC)networks.It ensures transmission reliability under the premise of high energy efficiency.Based on the analysis of the 6G MTC key performance indicators(KPIs)and scenario characteristics,this paper summarizes its requirements for radio access networks.Following this,the existing multiple access models are analyzed under these standards to determine UMA's advantages for 6G MTC according to its design characteristics.The critical technology of UMA is the design of its multiple-access coding scheme.Therefore,the existing UMA coding schemes from different coding paradigms are further summarized and compared.In particular,this paper comprehensively considers the energy efficiency and computational complexity of these schemes,studies the changes of the above two indexes with the increase of access scale,and considers the trade-off between the two.It is revealed by the above analysis that some guiding rules of UMA coding design.Finally,the open problems and potentials in this field are given for future research.
