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911.
A single-phased white emitting phosphor LaBSiO5:Dy3+ was successfully synthesized via a solid state reaction. The X-ray diffraction results confirmed that the doped Dy3+ ions did not change the lattice structure. Several strong excitation peaks of LaBSiO5:Dy3+ were found around 300–450 nm. Under excitation of 350 nm, the LaBSiO5:Dy3+ exhibited white emission by combining the two emission peaks at 478 and 574 nm corresponding to the typical 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions. The optimal substitution proportions of Dy3+ for La3+ was determined to be 1 mol% and the critical distance of Dy3+ was 25.9628 Å. Moreover, the CIE chromaticity coordinates of LaBSiO5:Dy3+ phosphor was (0.3116, 0.3474) which is close to the ideal white light coordinates (0.333, 0.333), indicating that the phosphor has a potential application as a single component ultraviolet-convertible white light emitting phosphor. 相似文献
912.
Tungsten oxide (WO3) films have been prepared on the synthesized TiO2 substrates from a sodium tungsten precursor via a hydrothermal method. X-ray diffraction, scanning electron microscopy and transmission electron microscopy analyses were used to investigate the effect of precursor concentrations on the structures and morphologies of the films. Ordered WO3 films were successfully synthesized on the as-grown TiO2 substrates. With the concentrations increasing from 0.001 M to 0.024 M, the morphologies of the films changed from multi-layer laminated structure to ladder-shaped lamellar structure finally columnar structure. The results also showed that with an increase in precursor concentration, the observed absorptions at 365 nm of the films increased until precursor concentration of 0.016 M, and then decreased with higher concentration. The film obtained with precursor concentration of 0.016 M on the TiO2 substrate had the best photochromic properties. 相似文献
913.
偏振模色散对光纤通信的影响 总被引:2,自引:1,他引:2
本文介绍了什么是单模光纤偏振模色散(PMD)及其形成的原因,ITU-T规定PMD≤0.5ps√km意味着什么,偏振模色散的统计特性,以及对光纤通信的影响。 相似文献
914.
J. H. Hao X. Mao C. H. Chen D. X. Lu 《Journal of Infrared, Millimeter and Terahertz Waves》1999,20(12):2113-2120
We report the optical responses of magnetic manganese oxide La2/3Ca1/3MnOδ thin films at room temperature. The voltage responses to a He-Ne laser at the wavelength of 0.63 μm and incident infrared (IR) power at the wavelength of 8-14 μm were measured. The measured signals were attributably to a bolometric response due to the heating of the sample by radiation. We report the optical responses in La2/3Ca1/3MnOδ thin films as a function of chopping frequency and bias current. The noise behavior around room temperature was also discussed. It is suggested that perovskite manganese oxide thin films are suitable candidates for uncooled optical detectors. 相似文献
915.
916.
在交流电渗流(ACEO)泵的研究中,一般忽略电极厚度的影响;而三维交流电渗流泵通过将电极厚度设计成台阶形式后,可以大大提高电渗流泵的流量。数值研究了电极台阶高度对三维交流电渗流泵流量的影响。研究发现:在驱动电压幅值不变的条件下,随着台阶高度的增加,三维交流电渗流泵流量也会增大;而当台阶高度增加到一定程度后,流量又会随着台阶高度的增加而减小。因此,在三维交流电渗流泵的设计制造中,需要优化电极的台阶高度,选择合适的台阶高度可以极大地提高电渗流泵的流量。通过和传统交流电渗流泵的比较,还研究了三维交流电渗流泵对流量的增强效果。结果表明:在相同模型尺寸参数下,优化台阶高度后的三维交流电渗流泵能极大提高流量。 相似文献
917.
918.
Shuai Wang Chonggang Wang Kai Peng Guang Tan Hongbo Jiang Yan Dong 《Wireless Networks》2014,20(5):1023-1036
Energy efficient broadcast is indispensable for many applications in wireless ad hoc networks. It has been proved that network coding has great potential to improve performance in terms of energy consumption in wireless ad hoc networks. However, the power of network coding depends on the availability of coding opportunities, which in turns depends on how routing paths are established. It is thus beneficial to establish paths in such a way that more coding opportunities are created. By combining network coding and connected dominating set (CDS), we explore energy minimal broadcast protocols in wireless ad hoc networks. The rationale behind this combination is that CDS provides better chances for data flows to intersect, which means more coding opportunities. We design a scheme, named NCDS, that uses network coding over connected dominating set, to reduce energy consumption. Analysis and experimental results show that NCDS outperforms broadcast algorithms that use CDS or network coding alone. 相似文献
919.
为了提高嵌入算法的整体性能,提出一种基于三 差值直方图平移和互补嵌入的彩色 图像可逆信息 隐藏算法。利用色彩分量之间的相关性以及预测误差之间的关系减小差值,以增加差值直方 图的峰值。采 用三差值直方图平移和双重嵌入方法提高嵌入容量,两次嵌入过程中像素值沿相反方向扩展 ,部分像素值 扩展量相互抵消。选择两种不同的预测方向计算预测误差,以增加扩展量抵消的机会,解决 双重嵌入时图 像质量严重下降的难点问题。实验结果表明,本文算法在保证图像质量的同时大幅提高嵌入 容量,算法的整体性能优于其它同类算法。 相似文献
920.
Zhenxue Chen Guoyou Wang Jianguo Liu Chengyun Liu 《Journal of Infrared, Millimeter and Terahertz Waves》2006,27(12):1619-1624
A background forecast filter is presented to detect a small target under an infrared (IR) nature scene. By calculating the correlation of image pixels, the background around the small target could be forecasted. Subtracting the forecast background from original scene, the small targets would become outstanding. Experimental results show that the algorithm proposed has better performance with respect to probability of detection and less computation complexity. 相似文献