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Studies of Large-scale Antenna Beamforming Technology
Ma LiJie 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.11
The large-scale antenna has the advantage of application is strong, it can greatly improve the average throughput of the system, but also can save transmission power, becoming one of the key technologies of the fifth generation mobile communications. However, in FDD system, the sender configure a large number of antennas, the access of channel state information has become a problem to achieve; for this problem, we propose a bit allocation scheme, this scheme is based on jointly zero forcing beamforming, using random vector quantization method, and getting a better performance, the success of the application of traditional finite feedback technology to large-scale antenna system, the simulation results show the effectiveness and correctness of the proposed algorithm.
Lijie Tang,Yan Ma,Caixia Yang,Enxiang Liang,Hong Yin,Qiong Wan,Jiance Zhang,Wei Wang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.118 No.-
Flexible energy storage devices are susceptible to damage, which might result in safety issues. In thispaper, a self-healing flexible P(AAPBA-co-P4-AC) gel electrolyte based on dynamic borate bond crosslinkingstrategy is reported. On the one hand, it is simple to process into complicated shapes or patterns,and on the other hand, it could rapidly return to its original state after stress damage. Even after ten timesself-healing, the gel has the same mechanical properties as the non-damaged gel. Furthermore, this gelcan also be applied in all-solid-state supercapacitors without the need of extra electrolytes. Becausethe gel has a large number of hydroxyl groups, it has a high affinity for the activated carbon electrode,and the supercapacitors can maintain 100% initial performance under various angles or strains. Afterten thousand times cycles charge–discharge, the supercapacitors using the gel after twenty times selfhealingprocess can retain 90% of its initial capacity, which is only 4% lower than the non-damagingsupercapacitors, demonstrating high self-healing ability.
A Novel Technique for Dressing Fixed Abrasive Lapping Pad with Abrasive Water Jet
Zhankui Wang,Yakun Yang,Zhao Zhang,Minghua Pang,Mingchao Liang,Lijie Ma,Jianxiu Su 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.6
The dressing method and dressing quality of the fixed abrasive lapping pad significantly impact the processing efficiency and surface quality of the workpiece material. Aiming at the problems of poor dressing effect and high damage degree of the lapping pad in the existing fixed abrasive dressing technology, a new technology using abrasive water jet for dressing is proposed. The self-developed abrasive water jet system was used to conduct a dressing test on a fixed abrasive lapping pad with a copper content of 30%. The influence of jet pressure, nozzle target distance, abrasive concentration and injection angle on the dressing effect were discussed, and the influence mechanism was analyzed by discrete element simulation. The results show that the dressing effect of the abrasive water jet is good. The dressing quality first increases and then decreases with the increase of jet pressure, nozzle target distance and injection angle, and increases with the increase of abrasive concentration. The influence mechanism of each parameter is closely related to the residual height of the lapping pad surface after dressing. The higher the residual height, the rougher the lapping pad surface, and the better the dressing effect of the lapping pad.