We investigate the laser actions of 5at% Yb：Gd2xY2（1-x）SiO5 （Yb：GYSO; x = 0.1） crystals with different cutting directions, parallel and vertical to the growth axis. Our results show that the cutting direction of...We investigate the laser actions of 5at% Yb：Gd2xY2（1-x）SiO5 （Yb：GYSO; x = 0.1） crystals with different cutting directions, parallel and vertical to the growth axis. Our results show that the cutting direction of the sample plays an astonished role in the laser operation. The sample cut vertically to the growth axis possesses the favourable lasing characteristics. Its output power reaches 3.13 W at 1060nm with a slope efficiency of 44.68Yo when the absorbed pump power is 8.9 W. In contrast, the sample cut parallel reaches only 1.65 W at 1044 nm with a slope efficiency of 33.76% with absorbed pump power of 7.99 W. The absorption and emission spectra of the two samples are examined and the merit factor M is calculated. Our analysis is in agreement well with the experimental results. The wavelength tuning range of the superior sample covers from 1013.68 nm to 1084.82nm.展开更多
Optical transmittance and reflectance on ferroelectric BaTi2O5 glasses prepared recently by a containerless synthesis technique are measured at room temperature in the wavelength range 190-800nm. The fundamental absor...Optical transmittance and reflectance on ferroelectric BaTi2O5 glasses prepared recently by a containerless synthesis technique are measured at room temperature in the wavelength range 190-800nm. The fundamental absorption edge located around 340nm demonstrates the coloudess and transparent character of the glass. The optical band gap of 3.32eV has been estimated. The tail of the optical absorption near the fundamental absorption edge is found to follow the Urbach rule. Our analysis of the experimental spectra supports an indirect allowed interband transition between the valence band formed by O-2p orbitals and the conduction band formed by Ti-3d orbitals.展开更多
水下爆炸气泡的膨胀-收缩运动会持续多次,在此过程中将发生能量的相互转换。在爆炸水池内分别开展了20、40和60 g RS211装药的气泡运动光测试验,采用高速相机拍摄气泡多次脉动的演化过程,对图像进行智能化识别处理,得到气泡的脉动周期...水下爆炸气泡的膨胀-收缩运动会持续多次,在此过程中将发生能量的相互转换。在爆炸水池内分别开展了20、40和60 g RS211装药的气泡运动光测试验,采用高速相机拍摄气泡多次脉动的演化过程,对图像进行智能化识别处理,得到气泡的脉动周期和最大半径。在此基础上,理论分析了气泡多次脉动过程中势能、内能的转换机制。结果表明:第2次气泡脉动相对于第1次气泡脉动的余能率为0.31;气泡内能占总能的比例为5.4%~6.6%;工程计算时,可忽略气泡内能,采用气泡势能表征气泡能。展开更多
为提升从科学研究中识别潜在技术机会的精准性,本文提出一种融合语义分析与拓扑建模的科学-技术关联识别框架。结合BERTopic(bidirectional encoder representations from transformers topic modeling)主题建模、显式共词与隐式链路预...为提升从科学研究中识别潜在技术机会的精准性,本文提出一种融合语义分析与拓扑建模的科学-技术关联识别框架。结合BERTopic(bidirectional encoder representations from transformers topic modeling)主题建模、显式共词与隐式链路预测等方法,构建多维度科学-技术关联指标,采用TOPSIS-CRITIC(technique for order preference by similarity to ideal solution-criteria importance through intercriteria correlation)模型评估科学主题的创新性与技术发展的制约因素,从而识别出具有高发展潜力的技术方向。以高温超导领域为案例开展实证分析,识别出6个有发展潜力的技术机会,与领域前沿发展方向具有良好的一致性,验证了该方法的有效性与前瞻性。本文的创新点在于提出术语级链路预测方法解决科技术语隔阂问题,探索了融合语义与结构特征识别有发展潜力的技术机会的路径。展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 60578052 and 60544003, the Shanghai Rising-Star Programme under Grant No 07QA14060, and the National Basic Research Programme of China under Grant No 2006CB806002.
文摘We investigate the laser actions of 5at% Yb：Gd2xY2（1-x）SiO5 （Yb：GYSO; x = 0.1） crystals with different cutting directions, parallel and vertical to the growth axis. Our results show that the cutting direction of the sample plays an astonished role in the laser operation. The sample cut vertically to the growth axis possesses the favourable lasing characteristics. Its output power reaches 3.13 W at 1060nm with a slope efficiency of 44.68Yo when the absorbed pump power is 8.9 W. In contrast, the sample cut parallel reaches only 1.65 W at 1044 nm with a slope efficiency of 33.76% with absorbed pump power of 7.99 W. The absorption and emission spectra of the two samples are examined and the merit factor M is calculated. Our analysis is in agreement well with the experimental results. The wavelength tuning range of the superior sample covers from 1013.68 nm to 1084.82nm.
文摘Optical transmittance and reflectance on ferroelectric BaTi2O5 glasses prepared recently by a containerless synthesis technique are measured at room temperature in the wavelength range 190-800nm. The fundamental absorption edge located around 340nm demonstrates the coloudess and transparent character of the glass. The optical band gap of 3.32eV has been estimated. The tail of the optical absorption near the fundamental absorption edge is found to follow the Urbach rule. Our analysis of the experimental spectra supports an indirect allowed interband transition between the valence band formed by O-2p orbitals and the conduction band formed by Ti-3d orbitals.
文摘水下爆炸气泡的膨胀-收缩运动会持续多次,在此过程中将发生能量的相互转换。在爆炸水池内分别开展了20、40和60 g RS211装药的气泡运动光测试验,采用高速相机拍摄气泡多次脉动的演化过程,对图像进行智能化识别处理,得到气泡的脉动周期和最大半径。在此基础上,理论分析了气泡多次脉动过程中势能、内能的转换机制。结果表明:第2次气泡脉动相对于第1次气泡脉动的余能率为0.31;气泡内能占总能的比例为5.4%~6.6%;工程计算时,可忽略气泡内能,采用气泡势能表征气泡能。
文摘为提升从科学研究中识别潜在技术机会的精准性,本文提出一种融合语义分析与拓扑建模的科学-技术关联识别框架。结合BERTopic(bidirectional encoder representations from transformers topic modeling)主题建模、显式共词与隐式链路预测等方法,构建多维度科学-技术关联指标,采用TOPSIS-CRITIC(technique for order preference by similarity to ideal solution-criteria importance through intercriteria correlation)模型评估科学主题的创新性与技术发展的制约因素,从而识别出具有高发展潜力的技术方向。以高温超导领域为案例开展实证分析,识别出6个有发展潜力的技术机会,与领域前沿发展方向具有良好的一致性,验证了该方法的有效性与前瞻性。本文的创新点在于提出术语级链路预测方法解决科技术语隔阂问题,探索了融合语义与结构特征识别有发展潜力的技术机会的路径。
