古代瓷器、陶器、砖瓦和范土等文物的烧成温度区间不同,不同烧成温度的文物会对释光测年方法的适用性产生影响。本研究选择4种不同烧成温度的文物——上海青龙镇遗址出土的1件青釉瓷片、上海广富林遗址出土的1件陶片、山东龙山汉墓群出...古代瓷器、陶器、砖瓦和范土等文物的烧成温度区间不同,不同烧成温度的文物会对释光测年方法的适用性产生影响。本研究选择4种不同烧成温度的文物——上海青龙镇遗址出土的1件青釉瓷片、上海广富林遗址出土的1件陶片、山东龙山汉墓群出土的1件釉砖,以及三星堆出土的3件范土样品,使用多种释光测年方法进行测年。结果表明,对于陶瓷类文物的释光测年,可通过使用多种方法相互验证来提高测年结果准确度。基于最小损坏的取样原则,因少量样品无法有效地分离不同矿物,本研究对于每件陶瓷类文物样品采取混合矿物颗粒进行测年。结果表明:对于烧成温度较低(低于450℃)或烧成温度较高但烧成时间很短时的样品(如本研究中的范土样品,由于烧成温度太低,存在无法清空常规热释光法和前剂量法信号的问题,因此无法使用热释光法对范土样品准确定年),可使用钾长石pIR 50 IR 170信号单片再生(single-aliquot regenerative-dose,SAR)法进行测年;对于烧成温度介于约450~1150℃之间的样品(如本研究中的陶器和砖瓦样品),可针对其中的钾长石矿物使用常规热释光法和pIR 50 IR 170信号SAR法进行测年,而针对其中的石英矿物颗粒使用前剂量法测年——需注意的是前剂量法只适用于年代≤1500年的文物;对于烧成温度≥1150℃的样品(如本研究中的瓷器样品,由于其中的钾长石晶体大部分熔融成玻璃相无法使用常规热释光法和IRSL信号法测年),可针对样品内的石英矿物颗粒使用前剂量法和OSL信号SAR法测年。本研究初步证明光释光信号具有测定低温烧制文物年龄的潜力,具有更广泛的烧制温度适用范围。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
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
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
文摘古代瓷器、陶器、砖瓦和范土等文物的烧成温度区间不同,不同烧成温度的文物会对释光测年方法的适用性产生影响。本研究选择4种不同烧成温度的文物——上海青龙镇遗址出土的1件青釉瓷片、上海广富林遗址出土的1件陶片、山东龙山汉墓群出土的1件釉砖,以及三星堆出土的3件范土样品,使用多种释光测年方法进行测年。结果表明,对于陶瓷类文物的释光测年,可通过使用多种方法相互验证来提高测年结果准确度。基于最小损坏的取样原则,因少量样品无法有效地分离不同矿物,本研究对于每件陶瓷类文物样品采取混合矿物颗粒进行测年。结果表明:对于烧成温度较低(低于450℃)或烧成温度较高但烧成时间很短时的样品(如本研究中的范土样品,由于烧成温度太低,存在无法清空常规热释光法和前剂量法信号的问题,因此无法使用热释光法对范土样品准确定年),可使用钾长石pIR 50 IR 170信号单片再生(single-aliquot regenerative-dose,SAR)法进行测年;对于烧成温度介于约450~1150℃之间的样品(如本研究中的陶器和砖瓦样品),可针对其中的钾长石矿物使用常规热释光法和pIR 50 IR 170信号SAR法进行测年,而针对其中的石英矿物颗粒使用前剂量法测年——需注意的是前剂量法只适用于年代≤1500年的文物;对于烧成温度≥1150℃的样品(如本研究中的瓷器样品,由于其中的钾长石晶体大部分熔融成玻璃相无法使用常规热释光法和IRSL信号法测年),可针对样品内的石英矿物颗粒使用前剂量法和OSL信号SAR法测年。本研究初步证明光释光信号具有测定低温烧制文物年龄的潜力,具有更广泛的烧制温度适用范围。
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.
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.
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。
