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1.
Xi Shen Li-Peng Cao Jian-Fa Zhao Wei-Peng Wang Qing-Qing Liu Yuan Yao Jun-Jie Li Chang-Zhi Gu Ming-Wei Chen Chang-Qing Jin Ri-Cheng Yu 《Journal of the American Ceramic Society》2019,102(11):6469-6474
We propose the question of the modulated structures of copper oxide is caused by the [CuO2] in-plane oxygen vacancy or apical oxygen vacancy. Sr2CuO3+δ single-crystal samples were prepared using high-temperature and high-pressure methods. The major phase of Sr2CuO3+δ (δ = 0.4) single-crystal system is found to be constituted by the 5 a modulated structure with the Fmmm space group, which originates from the [CuO2] in-plane oxygen vacancy appearing in octahedral Cu-O. Besides, the presence of the [CuO2] in-plane oxygen vacancy may obliterate the superconductivity of the system. Experimental results deduce that the oxygen vacancy may appear in the apical oxygen sites in high-temperature copper oxide superconductors. 相似文献
2.
《Journal of the European Ceramic Society》2020,40(13):4578-4588
Trivalent erbium ions doped Bi2O3-B2O3 transparent glass ceramics containing CaF2 were prepared and characterized through X -ray diffraction, scanning electron microscopy, Fourier transform infrared absorption, optical absorption, and near infrared emission for 1.53 μm fiber lasers. The glass ceramics obtained by applying thermal treatment at 575 °C for 5 h and 575 °C for 10 h contain Bi3B5O12 and CaF2 crystallites. The Judd-Ofelt theory was applied to evaluate various spectroscopic and laser characteristic properties. The NIR emission corresponding to the 4I13/2 → 4I15/2 (∼1.53 μm) transition was studied by exciting the samples at 514.5 nm laser radiation. The stimulated emission cross-sections of ∼1.53 μm luminescence were also obtained applying the Mc Cumber theory. The experimental results confirm that the transparent glass ceramic obtained at a thermal treatment of 575 °C for 10 h is more suitable to design fiber lasers for diverse applications in the fields of industry, medicine and scientific research. 相似文献
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Real-time multimedia applications have to use forward error correction (FEC) anderror concealment techniques to cope with
losses in today’s best-effort Internet. The efficiency of these solutions is known however to depend on the correlation between
losses in the media stream. In this paper we investigate how the packet size distribution affects the packet loss process,
that is, the distribution of the number of lost packets in a block, the related FEC performance and the average loss run length.
We present mathematical models for the loss process of the MMPP+M/D/1/K and the MMPP+M/M/1/K queues; we validate the models
via simulations, and compare the results to simulation results with an MPEG-4 coded video trace. We conclude that the deterministic
packet size distribution (PSD) not only results in lower stationary loss probability than the exponential one, but also gives
a less correlated loss process, both at a particular average link load and at a particular stationary loss probability as
seen by the media stream.Our results show that for applications that can only measure the packet loss probability, the effects
of the PSD on FEC performance are higher in access networks, where a single multimedia stream might affect the multiplexing
behavior. Our results show that the effects of the PSD on FEC performance are higher in access networks, where a single multimedia
stream might affect the multiplexing behavior and thus can improve the queuing performance by decreasing the variance of its
PSD. 相似文献
5.
激光晶体材料的发展和思考 总被引:2,自引:0,他引:2
徐军 《激光与光电子学进展》2006,43(9):17-24
在分析激光晶体研究现状的基础上,指出其未来应用及主要发展趋势:高功率、大能量激光晶体;中红外激光晶体;蓝绿紫和可见光激光晶体;LD抽运超快激光增益和放大介质晶体。以上四个方向中,高功率、大能量全固态激光晶体材料和LD抽运超快激光晶体材料又是覆盖其他方向、带有共性基础科学问题的关键方向。着重报道了LD抽运超快激光晶体材料的最新研究进展。 相似文献
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射频板条CO_2激光器并联谐振技术的研究 总被引:1,自引:0,他引:1
本文利用周期性网络模型计算了射频板条CO2激光器电极的纵向电压分布.探讨了并联谐振技术在板条器件中获得成功运用的原因.提出了利用并联谐振技术进一步提高电压分布均匀性的两个途径. 相似文献
9.
本文论述了具有透明波导结构的量子阱半导体激光器及其光集成技术的其本原理及主要优点。尤其在实现高功率窄光束输出的光集成器件方面更显出其独特的优点。 相似文献
10.
介绍了国内首次研制的光缆CATV用1.3μmDFB激光器组件。组件工作频带达到1GHz,带内起伏〈1dB,组件的RIN〈-153dB/Hz;出纤光功率〉2mW,载噪比CNR〉50dB。首次实现用低反射尖锥端光纤的DFB激光器耦合。 相似文献