Owing to the abundance and low price of sodium,researches on sodium-ion batteries(SIBs)as a lithiumion battery(LIB)alternative are emerging as a consensus.It is crucial to develop electrode materials suitable for sodi...Owing to the abundance and low price of sodium,researches on sodium-ion batteries(SIBs)as a lithiumion battery(LIB)alternative are emerging as a consensus.It is crucial to develop electrode materials suitable for sodium storage.In recent years,two-dimensional(2 D)layered transition metal disulfide compounds(TMDs)have trigered interest in the realm of energy and environmental fields.In particular,MoSeis thought to be a suitable material for SIBs due to its wide original layer spacing and high conductivity.Herein,N-doped dual carbon-coated MoSewith multichannel paths(MoSe/multichannel carbon nanofibers(MCFs)@NC)is fabricated via electrospinning,followed by a selenation and carbonization process.The existence of a 3 D conductive network,abundant void spaces,and sufficient electron transportation pathways are conducive to rapid and fast charge transfer kinetics under volume expansion stress.When applied in SIBs,the MoSe/MCFs@NC shows a high capability(319 mA hg^(-1)at 10 A g^(-1)),as well as good cycling stability(303 mA h g^(-1)after 1100 cycles at 10 A g^(-1)).Furthermore,coupled with the Na_(3)V_(2)(PO_(4))_(2)O_(2)F cathode,the full cell also exhibits excellent performance.The theoretical calculation of the MoSe_(2)/MCFs@NC confirms that the superiority of its SIB performance is owing to the strong interaction between the double-doped carbon and MoSe.This scheme provides a wide space for preparing high-performance electrode materials for SIBs.展开更多
Often oilfield fractured horizontal wells produce water flowing in multiple directions.In this study,a method to identify such channeling paths is developed.The dual-medium model is based on the principle of inter-wel...Often oilfield fractured horizontal wells produce water flowing in multiple directions.In this study,a method to identify such channeling paths is developed.The dual-medium model is based on the principle of inter-well connectivity and considers the flow characteristics and related channeling terms.The Lorentz curve is drawn to qualitatively discern the geological type of the low-permeability fractured reservoir and determine the channeling direction and size.The practical application of such an approach to a sample oilfield shows that it can accurately identify the channeling paths of the considered low-permeability fractured reservoir and predict production performances according to the inter-well connectivity model.As a result,early detection of water channeling becomes possible,paving the way to real-time production system optimization in low-permeability fractured reservoirs.展开更多
Massive MIMO is one of tile enabling technologies tbr beyond 4G and 5G systems due to its ability to provide beamforming gain and reduce interference Dual-polarized antenna is widely adopted to accommodate a large num...Massive MIMO is one of tile enabling technologies tbr beyond 4G and 5G systems due to its ability to provide beamforming gain and reduce interference Dual-polarized antenna is widely adopted to accommodate a large number of antenna elements in limited space. However, current CSI（channel state information） feedback schemes developed in LTE for conventional MIMO systems are not efficient enough for massive MIMO systems since the overhead increases almost linearly with the number of antenna. Moreover, the codebook for massive MIMO will be huge and difficult to design with the LTE methodology. This paper proposes a novel CSI feedback scheme named layered Multi-paths Information based CSI Feedback （LMPIF）, which can achieve higher spectrum efficiency for dual-polarized antenna system with low feedback overhead. The MIMO channel is decomposed into long term components （multipath directions and amplitudes） and short term components （multipath phases）. The relationship between the two components and the optimal precoder is derived in closed form. To reduce the overhead, different granularities in feedback time have been applied for the long term components and short term components Link and system level simulation results prove that LMPIF can improve performance considerably with low CSI feedback overhead.展开更多
基金financially supported by the National Natural Science Foundation of China(51801030)the Natural Science Foundation of Guangdong Providence(2018A030310571)+2 种基金the Science and Technology Development Plan of Suzhou(ZXL2021176)China Postdoctoral Science Foundation(2022M711686)Jiangsu Provincial Funds for the Young Scholars(BK20190978)。
文摘Owing to the abundance and low price of sodium,researches on sodium-ion batteries(SIBs)as a lithiumion battery(LIB)alternative are emerging as a consensus.It is crucial to develop electrode materials suitable for sodium storage.In recent years,two-dimensional(2 D)layered transition metal disulfide compounds(TMDs)have trigered interest in the realm of energy and environmental fields.In particular,MoSeis thought to be a suitable material for SIBs due to its wide original layer spacing and high conductivity.Herein,N-doped dual carbon-coated MoSewith multichannel paths(MoSe/multichannel carbon nanofibers(MCFs)@NC)is fabricated via electrospinning,followed by a selenation and carbonization process.The existence of a 3 D conductive network,abundant void spaces,and sufficient electron transportation pathways are conducive to rapid and fast charge transfer kinetics under volume expansion stress.When applied in SIBs,the MoSe/MCFs@NC shows a high capability(319 mA hg^(-1)at 10 A g^(-1)),as well as good cycling stability(303 mA h g^(-1)after 1100 cycles at 10 A g^(-1)).Furthermore,coupled with the Na_(3)V_(2)(PO_(4))_(2)O_(2)F cathode,the full cell also exhibits excellent performance.The theoretical calculation of the MoSe_(2)/MCFs@NC confirms that the superiority of its SIB performance is owing to the strong interaction between the double-doped carbon and MoSe.This scheme provides a wide space for preparing high-performance electrode materials for SIBs.
文摘Often oilfield fractured horizontal wells produce water flowing in multiple directions.In this study,a method to identify such channeling paths is developed.The dual-medium model is based on the principle of inter-well connectivity and considers the flow characteristics and related channeling terms.The Lorentz curve is drawn to qualitatively discern the geological type of the low-permeability fractured reservoir and determine the channeling direction and size.The practical application of such an approach to a sample oilfield shows that it can accurately identify the channeling paths of the considered low-permeability fractured reservoir and predict production performances according to the inter-well connectivity model.As a result,early detection of water channeling becomes possible,paving the way to real-time production system optimization in low-permeability fractured reservoirs.
基金supported by the National High-Tech R&D Program(863 Program 2015AA01A705)
文摘Massive MIMO is one of tile enabling technologies tbr beyond 4G and 5G systems due to its ability to provide beamforming gain and reduce interference Dual-polarized antenna is widely adopted to accommodate a large number of antenna elements in limited space. However, current CSI（channel state information） feedback schemes developed in LTE for conventional MIMO systems are not efficient enough for massive MIMO systems since the overhead increases almost linearly with the number of antenna. Moreover, the codebook for massive MIMO will be huge and difficult to design with the LTE methodology. This paper proposes a novel CSI feedback scheme named layered Multi-paths Information based CSI Feedback （LMPIF）, which can achieve higher spectrum efficiency for dual-polarized antenna system with low feedback overhead. The MIMO channel is decomposed into long term components （multipath directions and amplitudes） and short term components （multipath phases）. The relationship between the two components and the optimal precoder is derived in closed form. To reduce the overhead, different granularities in feedback time have been applied for the long term components and short term components Link and system level simulation results prove that LMPIF can improve performance considerably with low CSI feedback overhead.
