A series of Er3＋, Tm3＋ and Yb3＋ doped Gd3Ga5O12 nanocrystals were prepared by a combustion method. The X-ray diffraction （XRD）, field emission scanning electron microscope （FESEM） and upconversion （UC） emissi...A series of Er3＋, Tm3＋ and Yb3＋ doped Gd3Ga5O12 nanocrystals were prepared by a combustion method. The X-ray diffraction （XRD）, field emission scanning electron microscope （FESEM） and upconversion （UC） emission spectra were used to characterize the samples. The results of XRD indicate that Gd3Ga5O12：Er3＋, Tm3＋, Yb3＋ nanocrystals with cubic phase can be obtained. Under the excitation of a 980 nm laser, the different rare earth ions doped Gd3Ga5O12 nanoerystals show upconversion luminescence involving the green emission attributed to the ^2H11/2→^4I15/2, 4^S3/2→^4I15/2 transitions of Er3＋ ions, respectively, the red emissions assigned to the ^4F9/2→^4I15/2 transitions of Er3＋ ions and the ^1G4→^3F4 as well as 3F2,3→^3H6 transitions of Tm3＋ ions, respectively, the blue emission attributed to ^1G4→^3H6 transitions of Tm3＋ ions, and the near-infrared assigned to the ^3H4→^3H6 transitions of Tm3＋ ions. The CIE coordinates for the samples are calculated. The dependence of their upconversion luminescence properties on Yb3＋ ion concentration is investieated.展开更多
针对鸟群优化算法迭代初期种群多样性不足、迭代后期收敛速度慢、易陷入局部最优解等问题,提出一种融合柯西变异的鸟群与算术混合优化算法(hybrid algorithm of bird swarm algorithm and arithmetic optimization algorithm based on C...针对鸟群优化算法迭代初期种群多样性不足、迭代后期收敛速度慢、易陷入局部最优解等问题,提出一种融合柯西变异的鸟群与算术混合优化算法(hybrid algorithm of bird swarm algorithm and arithmetic optimization algorithm based on Cauchy mutation,HBSAAOA)。利用算术优化算法中乘除算子的高分布性对BSA中生产者的位置进行更新,以提高种群多样性,增强全局搜索能力。引入随机搜索策略和柯西变异策略来生成候选解,对后期局部开发阶段进行扰动,以增强算法跳出局部最优解的能力并提高收敛速度。利用贪婪策略对最优个体进行选择并替代较差的个体,从而提高解的质量。通过对23个经典测试函数以及部分CEC2014基准函数进行仿真实验,并将HBSAAOA应用到两个工程应用问题上,结果表明改进策略有效,改进算法的收敛速度更快、寻优精度更高,并且鲁棒性更好。展开更多
基金Funded by the Science and Technology Research Project of Department of Education of Liaoning Province,China(No.L2011063)
文摘A series of Er3＋, Tm3＋ and Yb3＋ doped Gd3Ga5O12 nanocrystals were prepared by a combustion method. The X-ray diffraction （XRD）, field emission scanning electron microscope （FESEM） and upconversion （UC） emission spectra were used to characterize the samples. The results of XRD indicate that Gd3Ga5O12：Er3＋, Tm3＋, Yb3＋ nanocrystals with cubic phase can be obtained. Under the excitation of a 980 nm laser, the different rare earth ions doped Gd3Ga5O12 nanoerystals show upconversion luminescence involving the green emission attributed to the ^2H11/2→^4I15/2, 4^S3/2→^4I15/2 transitions of Er3＋ ions, respectively, the red emissions assigned to the ^4F9/2→^4I15/2 transitions of Er3＋ ions and the ^1G4→^3F4 as well as 3F2,3→^3H6 transitions of Tm3＋ ions, respectively, the blue emission attributed to ^1G4→^3H6 transitions of Tm3＋ ions, and the near-infrared assigned to the ^3H4→^3H6 transitions of Tm3＋ ions. The CIE coordinates for the samples are calculated. The dependence of their upconversion luminescence properties on Yb3＋ ion concentration is investieated.
文摘针对鸟群优化算法迭代初期种群多样性不足、迭代后期收敛速度慢、易陷入局部最优解等问题,提出一种融合柯西变异的鸟群与算术混合优化算法(hybrid algorithm of bird swarm algorithm and arithmetic optimization algorithm based on Cauchy mutation,HBSAAOA)。利用算术优化算法中乘除算子的高分布性对BSA中生产者的位置进行更新,以提高种群多样性,增强全局搜索能力。引入随机搜索策略和柯西变异策略来生成候选解,对后期局部开发阶段进行扰动,以增强算法跳出局部最优解的能力并提高收敛速度。利用贪婪策略对最优个体进行选择并替代较差的个体,从而提高解的质量。通过对23个经典测试函数以及部分CEC2014基准函数进行仿真实验,并将HBSAAOA应用到两个工程应用问题上,结果表明改进策略有效,改进算法的收敛速度更快、寻优精度更高,并且鲁棒性更好。
