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| 1 | Joint Beamforming Optimization for Reconfigurable Intelligent Surface-Enabled MISO-OFDM Systems显示文摘In this paper,we investigate the reconfigurable intelligent surface(RIS)-enabled multiple-input-single-output orthogonal frequency division multiplexing(MISO-OFDM)system under frequency-selective channels,and propose a low-complexity alternating optimization(AO)based joint beamforming and RIS phase shifts optimization algorithm to maximize the achievable rate.First,with fixed RIS phase shifts,we devise the optimal closedform transmit beamforming vectors corresponding to different subcarriers.Then,with given active beamforming vectors,near-optimal RIS reflection coefficients can be determined efficiently leveraging fractional programming(FP)combined with manifold optimization(MO)or majorization-minimization(MM)framework.Additionally,we also propose a heuristic RIS phase shifts design approach based on the sum of subcarrier gain maximization(SSGM)criterion requiring lower complexity.Numerical results indicate that the proposed MO/MM algorithm can achieve almost the same rate as the upper bound achieved by the semidefinite relaxation(SDR)algorithm,and the proposed SSGM based scheme is only slightly inferior to the upper bound while has much lower complexity.These results demonstrate the effectiveness of the proposed algorithms. | Keming Feng Xiao Li Yu Han Yijian Chen | 2021 | China Communications2021，18，3： | 6 |
| 2 | Quantifying the characteristics of particulate matters captured by urban plants using an automatic approach显示文摘It is widely accepted that urban plant leaves can capture airborne particles. Previous studies on the particle capture capacity of plant leaves have mostly focused on particle mass and/or size distribution. Fewer studies, however, have examined the particle density, and the size and shape characteristics of particles, which may have important implications for evaluating the particle capture efficiency of plants, and identifying the particle sources. In addition, the role of different vegetation types is as yet unclear. Here, we chose three species of different vegetation types, and firstly applied an object-based classification approach to automatically identify the particles from scanning electron microscope(SEM)micrographs. We then quantified the particle capture efficiency, and the major sources of particles were identified. We found(1) Rosa xanthina Lindl(shrub species) had greater retention efficiency than Broussonetia papyrifera(broadleaf species) and Pinus bungeana Zucc.(coniferous species), in terms of particle number and particle area cover.(2) 97.9% of the identified particles had diameter ≤10 μm, and 67.1% of them had diameter ≤2.5 μm. 89.8% of the particles had smooth boundaries, with 23.4% of them being nearly spherical.(3) 32.4%–74.1% of the particles were generated from bare soil and construction activities, and 15.5%–23.0% were mainly from vehicle exhaust and cooking fumes. | Jingli Yan Lin Lin Weiqi Zhou Lijian Han Keming Ma | 2016 | Journal of Environmental Sciences2016，28，1： | 3 |
| 3 | Direct Liquefaction Behaviors of Bulianta Coal and It-s Macerals显示文摘 | JIN Lijun HAN Keming WANG Jianyou | 2014 | Fuel Pro- cessing Technology2014，128，： | 1 |
| 4 | China's Production of Organic Fertilizer and Development Direction[J]显示文摘 | HAN Lianghao(韩良浩) CHU Jixing(初吉兴) HAN Keming(韩克敏) | | 农业科技通讯0，，： | 1 |
| 5 | Fuzzy comprehen- sive evaluation for stability of strata over gob influenced by construction loads 显示文摘 | Han Keming Li Fengming Li Hongyan | 2012 | Energy Procedia2012，，16： | 1 |
| 6 | An Experimental Research of Natural Circulation Heat Transfer for PRHR Heat Exchanger in AP1000显示文摘 | Minghui Duan Yuzhou Chen Yvfeng Lv Weiqing Li Keming Bi Wei Wang Kaiwen Du Han Wang | 2016 | Journal of Energy and Power Engineering2016，10，9： | 0 |
| 7 | Corrosion Resistance of Fused Cr_2O_3-Al_2O_3 Grains with Different Compositions显示文摘Six kinds of Cr2O3 Al2O3 fused grains ( the mass percent of Cr2O3 was 15% ,40% ,50% ,60% ,85% and 99% ,respectively) were prepared using chrome green and Al2O3 powder as starting materials by electrofusion,named as CR15,CR40,CR50,CR60,CR85, and CR99,respectively. The corrosion resistance of the six kinds of Cr2O3 Al2O3 fused grains ( 4 1 mm) was studied using rotary slag corrosion method. The results show that: ( 1) the corrosion resistance of the fused grains increases with the Cr2O3 content and the grain size increasing; ( 2) the grains of CR99 and CR85 with higher Cr2O3 content are corroded at the slag surface layer,because FeO and Al2O3 in the slag corrode the grains; FeO reacts with Cr2O3 in the aggregates forming ( Fe,Cr) 3O4 spinel firstly,and the spinel reacts with other phases forming composite spinel; when FeO is fully consumed,Al2O3 penetrated into the grains reacts with Cr2O3 forming Al2O3 Cr2O3 solid solution on the grains surface; ( 3) for CR60,the corrosion exists both in the slag surface layer and in the penetration layer; in the penetration layer,CaO and SiO2 react with Al2O3 in Al2O3 Cr2O3 solid solution forming anorthite, gehlenite, and glass phase; the grains of CR50,CR40 and CR15 have the same corrosion mechanism with CR60 in the penetration layer. | WANG Han LAN Heqing GENG Keming LV Shiping FANG Xu | 2012 | China's Refractories2012，21，2： | 0 |
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