A non-orthogonal multiple access(NOMA) power allocation scheme on the basis of the sparrow search algorithm(SSA) is proposed in this work. Specifically, the logarithmic utility function is utilized to address the pote...A non-orthogonal multiple access(NOMA) power allocation scheme on the basis of the sparrow search algorithm(SSA) is proposed in this work. Specifically, the logarithmic utility function is utilized to address the potential fairness issue that may arise from the maximum sum-rate based objective function and the optical power constraints are set considering the non-negativity of the transmit signal, the requirement of the human eyes safety and all users' quality of service(Qo S). Then, the SSA is utilized to solve this optimization problem. Moreover, to demonstrate the superiority of the proposed strategy, it is compared with the fixed power allocation(FPA) and the gain ratio power allocation(GRPA) schemes. Results show that regardless of the number of users considered, the sum-rate achieved by SSA consistently outperforms that of FPA and GRPA schemes. Specifically, compared to FPA and GRPA schemes, the sum-rate obtained by SSA is increased by 40.45% and 53.44% when the number of users is 7, respectively. The proposed SSA also has better performance in terms of user fairness. This work will benefit the design and development of the NOMA-visible light communication(VLC) systems.展开更多
To improve the quality of the illumination distribution,one novel indoor visible light communication(VLC)system,which is jointly assisted by the angle-diversity transceivers and simultaneous transmission and reflectio...To improve the quality of the illumination distribution,one novel indoor visible light communication(VLC)system,which is jointly assisted by the angle-diversity transceivers and simultaneous transmission and reflection-intelligent reflecting surface(STAR-IRS),has been proposed in this work.A Harris Hawks optimizer algorithm(HHOA)-based two-stage alternating iteration algorithm(TSAIA)is presented to jointly optimize the magnitude and uniformity of the received optical power.Besides,to demonstrate the superiority of the proposed strategy,several benchmark schemes are simulated and compared.Results showed that compared to other optimization strategies,the TSAIA scheme is more capable of balancing the average value and variance of the received optical power,when the maximal ratio combining(MRC)strategy is adopted at the receiver.Moreover,as the number of the STAR-IRS elements increases,the optical power variance of the system optimized by TSAIA scheme would become smaller while the average optical power would get larger.This study will benefit the design of received optical power distribution for indoor VLC systems.展开更多
目的探讨军事飞行人员脑海绵状血管畸形(cerebral cavernous malformations,CCM)的诊疗及航空医学鉴定。方法收集空军特色医学中心2015—2021年收治的诊断为CCM的飞行人员临床资料及航空医学鉴定结论,结合国内外相关鉴定案例及文献进行...目的探讨军事飞行人员脑海绵状血管畸形(cerebral cavernous malformations,CCM)的诊疗及航空医学鉴定。方法收集空军特色医学中心2015—2021年收治的诊断为CCM的飞行人员临床资料及航空医学鉴定结论,结合国内外相关鉴定案例及文献进行分析。结果共收集10例飞行人员病例,均为男性,年龄20~41岁,平均年龄28.3岁。其中飞行员8例,空中战技勤人员2例。飞行时间110~4000 h,平均飞行时间1102.0 h。病灶大小3~12 mm,其中<5 mm 2例,5~10 mm 6例,>10 mm 2例。病灶位置包括枕叶(1例)、额叶(4例)、颞叶(2例)、小脑半球(3例),均位于皮层下。10例飞行人员中,仅有1例首发症状为颅内出血(右侧小脑半球),予以手术治疗。3例飞行人员处于地面观察期,航空医学鉴定结论为暂时飞行不合格。其余7例飞行人员随访时间均超过6个月,复查MRI示病变均无改变、脑电图无异常,其中2例空中战技勤人员航空医学鉴定结论为飞行合格;1例直升机飞行员鉴定结论为飞行合格(限副驾驶),2例双座歼击机飞行员鉴定结论分别为飞行合格(限双座机)、飞行合格,2例单座歼击机飞行员鉴定结论为更改原机种后飞行合格(限轰炸机、运输机和直升机)。结论对于CCM军事飞行人员应根据有无症状、病变部位和大小、失能可能性评估、治疗效果、地面观察随访结果以及飞行机种和职别做出航空医学鉴定结论。展开更多
基金supported by the Cooperative Research Project between China Coal Energy Research Institute Co.,Ltd. and Xidian University (No.N-KY-HX-1101-202302-00725)the Key Research and Development Program of Shaanxi Province (No.2017ZDCXL-GY-06-02)。
文摘A non-orthogonal multiple access(NOMA) power allocation scheme on the basis of the sparrow search algorithm(SSA) is proposed in this work. Specifically, the logarithmic utility function is utilized to address the potential fairness issue that may arise from the maximum sum-rate based objective function and the optical power constraints are set considering the non-negativity of the transmit signal, the requirement of the human eyes safety and all users' quality of service(Qo S). Then, the SSA is utilized to solve this optimization problem. Moreover, to demonstrate the superiority of the proposed strategy, it is compared with the fixed power allocation(FPA) and the gain ratio power allocation(GRPA) schemes. Results show that regardless of the number of users considered, the sum-rate achieved by SSA consistently outperforms that of FPA and GRPA schemes. Specifically, compared to FPA and GRPA schemes, the sum-rate obtained by SSA is increased by 40.45% and 53.44% when the number of users is 7, respectively. The proposed SSA also has better performance in terms of user fairness. This work will benefit the design and development of the NOMA-visible light communication(VLC) systems.
基金supported by the National Natural Science Foundation of China(No.62071365)the Key Research and Development Program of Shaanxi Province(No.2017ZDCXL-GY-06-02).
文摘To improve the quality of the illumination distribution,one novel indoor visible light communication(VLC)system,which is jointly assisted by the angle-diversity transceivers and simultaneous transmission and reflection-intelligent reflecting surface(STAR-IRS),has been proposed in this work.A Harris Hawks optimizer algorithm(HHOA)-based two-stage alternating iteration algorithm(TSAIA)is presented to jointly optimize the magnitude and uniformity of the received optical power.Besides,to demonstrate the superiority of the proposed strategy,several benchmark schemes are simulated and compared.Results showed that compared to other optimization strategies,the TSAIA scheme is more capable of balancing the average value and variance of the received optical power,when the maximal ratio combining(MRC)strategy is adopted at the receiver.Moreover,as the number of the STAR-IRS elements increases,the optical power variance of the system optimized by TSAIA scheme would become smaller while the average optical power would get larger.This study will benefit the design of received optical power distribution for indoor VLC systems.
文摘目的探讨军事飞行人员脑海绵状血管畸形(cerebral cavernous malformations,CCM)的诊疗及航空医学鉴定。方法收集空军特色医学中心2015—2021年收治的诊断为CCM的飞行人员临床资料及航空医学鉴定结论,结合国内外相关鉴定案例及文献进行分析。结果共收集10例飞行人员病例,均为男性,年龄20~41岁,平均年龄28.3岁。其中飞行员8例,空中战技勤人员2例。飞行时间110~4000 h,平均飞行时间1102.0 h。病灶大小3~12 mm,其中<5 mm 2例,5~10 mm 6例,>10 mm 2例。病灶位置包括枕叶(1例)、额叶(4例)、颞叶(2例)、小脑半球(3例),均位于皮层下。10例飞行人员中,仅有1例首发症状为颅内出血(右侧小脑半球),予以手术治疗。3例飞行人员处于地面观察期,航空医学鉴定结论为暂时飞行不合格。其余7例飞行人员随访时间均超过6个月,复查MRI示病变均无改变、脑电图无异常,其中2例空中战技勤人员航空医学鉴定结论为飞行合格;1例直升机飞行员鉴定结论为飞行合格(限副驾驶),2例双座歼击机飞行员鉴定结论分别为飞行合格(限双座机)、飞行合格,2例单座歼击机飞行员鉴定结论为更改原机种后飞行合格(限轰炸机、运输机和直升机)。结论对于CCM军事飞行人员应根据有无症状、病变部位和大小、失能可能性评估、治疗效果、地面观察随访结果以及飞行机种和职别做出航空医学鉴定结论。
