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- 저자 : Zhongcai Li (검색결과 4 건)
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Partly Random Multiple Weighting Matrices Selection for Orthogonal Random Beamforming
Li Tan,Zhongcai Li,Chao Xu,Desheng Wang 한국통신학회 2016 Journal of communications and networks Vol.18 No.6
In the multi-user multiple-input multiple-output(MIMO) system, orthogonal random beamforming (ORBF)scheme is proposed to serve multiple users simultaneously in orderto achieve the multi-user diversity gain. The opportunistic spacedivisionmultiple access system (OSDMA-S) scheme performs multipleweighting matrices during the training phase and choosesthe best weighting matrix to be used to broadcast data during thetransmitting phase. The OSDMA-S scheme works better than theoriginal ORBF by decreasing the inter-user interference duringthe transmitting phase. To save more time in the training phase,a partly random multiple weighting matrices selection scheme isproposed in this paper. In our proposed scheme, the Base Stationdoes not need to use several unitary matrices to broadcast pilotsymbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels witha set of pre-saved unitary matrices and the channel status informationgained from the broadcasting operation. The signal-tointerferenceand noise ratio (SINR) of each beam in each virtualequivalent channel is calculated and fed back to the base stationfor the weighting matrix selection and multi-user scheduling. Accordingto the theoretical analysis, the proposed scheme relativelyexpands the transmitting phase and reduces the interactive complexitybetween the Base Station and subscribers. The asymptoticanalysis and the simulation results show that the proposed schemeimproves the throughput performance of the multi-user MIMOsystem.
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Partly Random Multiple Weighting Matrices Selection for Orthogonal Random Beamforming
Tan, Li,Li, Zhongcai,Xu, Chao,Wang, Desheng The Korea Institute of Information and Commucation 2016 Journal of communications and networks Vol.18 No.6
In the multi-user multiple-input multiple-output (MIMO) system, orthogonal random beamforming (ORBF) scheme is proposed to serve multiple users simultaneously in order to achieve the multi-user diversity gain. The opportunistic space-division multiple access system (OSDMA-S) scheme performs multiple weighting matrices during the training phase and chooses the best weighting matrix to be used to broadcast data during the transmitting phase. The OSDMA-S scheme works better than the original ORBF by decreasing the inter-user interference during the transmitting phase. To save more time in the training phase, a partly random multiple weighting matrices selection scheme is proposed in this paper. In our proposed scheme, the Base Station does not need to use several unitary matrices to broadcast pilot symbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels with a set of pre-saved unitary matrices and the channel status information gained from the broadcasting operation. The signal-to-interference and noise ratio (SINR) of each beam in each virtual equivalent channel is calculated and fed back to the base station for the weighting matrix selection and multi-user scheduling. According to the theoretical analysis, the proposed scheme relatively expands the transmitting phase and reduces the interactive complexity between the Base Station and subscribers. The asymptotic analysis and the simulation results show that the proposed scheme improves the throughput performance of the multi-user MIMO system.
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Effect of Molybdate Conversion Coating of Magnesium Alloy Reinforced by Micro-arc Oxidation
Hongda Zhu,Xuetian Li,Xiurong Guan,Zhongcai Shao 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
In order to enhance the corrosion resistance of molybdate conversion coating, the molybdate coating is subjected to micro-arcoxidation treatment in electrolyte with Na2SiO3as a main salt. The electrochemical behavior and corrosion weight loss ofdifferent coating were studied. The surface morphology, element composition, roughness and phase composition of differentcoatings were analyzed by SEM, EDS, laser confocal microscopy and XRD, the growth process of different micro-arcoxidation coatings was explored. The results shows that the arcing voltage of the molybdate coating enhanced by micro-arcoxidation is significantly reduced, the corrosion potential is shifted to the right, and the corrosion weightlessloss of thecoating is the lowest, compared with the molybdate coating and the micro-arc oxidation coating. Micro-arc oxidation on thesurface of the molybdate coating is beneficial to the formation of MgAl2O4and the production of new phase is MoSi2,whichcan better improve the corrosion resistance of the molybdate coating. The micro-arc oxide coating does not form a ceramicfilm with a pore structure at the moment of arcing. As the micro-arc oxidation time prolongs, the ceramic film is graduallyformed. When the time reaches 60 s, the ceramic film is completely formed.
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Wenhui Ma,Zhaochuan Yu,Zhongcai Li,Jing Wen,Baoru Zhao,Yong Zhang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2020 NANO Vol.15 No.03
Owing to the hazardness, the sensitive and selective detection of cyanide (CN-) in water or water-containing systems has still been a puzzle plaguing scientists all around the world. In this paper, a novel fluorescence probe based on covalently functionalized graphene oxide (GO) by aminocoumarin for highly selective detection of CN- in deionized water was prepared under the action of EDC/NHS. This probe bears aminocoumarin group as the recognition site and fluorophore, and its fluorescence quantum yield is increased by 0.07. Simultaneously, by loading on GO, the dispersibility, selectivity and reversibility were soundly improved, which facilitated the detection process. The fluorescence spectra showed that the probe has high selectivity and sensitivity for cyanide, and has potential application in real water.
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