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氮化硼纤维是一种新型的无机纤维。它的制备是以氧化硼纤维为前躯体,在氨气氛中加热形成部分氮化的一次氮化硼纤维,再经热处理过程转化成主要成分为氮化硼的二次氮化硼纤维。本文应用透射电镜和扫描电镜深入研究了氮化硼纤维的晶体结构、晶粒形貌与大小、结晶度、取向性以及纤维的内部缺隐与表面缺陷。首先应用透射电镜的选区电子衍射技术对几种不同工艺条件下制备的一次氮化硼纤维、二次氮化硼纤维试样与六方晶系氮化硼制品试样进行了晶体结构的对比分析。结果表明,本研究的氮化硼纤维是一种取 相似文献
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Recent progress in long-distance in-Fiber Bragg Grating (FBG) sensor systems at University of Electronic Science & Technology of China (UESTC) is reviewed in this paper. Two novel approaches with a 50km transmission distance are proposed and demonstrated. The first one is based on the combination of bidirectional Raman amplification and a dual Erbium-Doped Fiber (EDF) configuration. A good Signal-to-Noise Ratio (SNR) of ~16dB is achieved with only a pump power of ~280 mW, which is ~10 dB higher than that without amplification. The second is based on a novel tunable fiber ring laser configuration with hybrid Raman/EDFA configuration. Experimental results show that an excellent optical SNR of-~60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of ~170 mW and a low EDFA pump power of~40 mW at wavelength of 980 nm. It is anticipated that these long-distance FBG sensing systems could find important applications in health monitoring of large infra-structures, such as oil or gas pipelines, ultra-long bridges and tunnels, river banks, and so on. 相似文献
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FU Hong-yan OU Hai-yan CHEN Da-ru XIAO Yun HE Sai-ling 《光电子快报》2007,3(6):406-409
The tunable microwave photonic filter based on a fiber ring and erbium-doped fiber amplifier (EDFA) was proposed. By introducing a section of erbium-doped fiber (EDF) into the fiber ring, the loss of the signal can be compensated by the EDFA gain through adjusting the pump power. This can largely increase the number of the effective sampling taps, and then improve the performance of the microwave photonic filter notably. When the pump power was set to be 42.7 roW, a microwave bandpass filter with the 3-dB bandwidth of 0.15 MHz, the Q factor up to 100 and extinction ratio up to 20 dB was achieved. By employing a tunable optical delay line in the above fiber ring, a tunable microwave photonic filter has been realized through tuning the length of the optical delay line. The proposed tunable microwave photonic filter can fred great applications in microwave signal processing and ROF system. 相似文献
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远红外丙纶的组成与远红外发射性能 总被引:1,自引:0,他引:1
系统测试了含有不同种类,不同重量远红外粉的聚丙烯纤维100℃远红外发射率,发现纤维中的远红外粉添加量存在最佳值,该最佳值的位置与远红外粉的种类有关,一般在6Wt%~20wt.%重量百分含量,在最佳远红外粉含量时,纤维的5~25μm全波长发射率存在峰值,该峰值的存在为得到低成本,高远红外发射率的远红外纤维提供了实验依据,同时测试了采用最佳值时的组成纺制出的远红外丙化针织布不同温度下的远红外发射率,并 相似文献
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We report on fiber Bragg gratings in all-solid photonie bandgap fiber that was composed of a triangular array of high-index Ge-doped rods in pure silica background with fluorine-doped index-depressed layer surrounding the Ge-doped rod. Fiber Bragg gratings were photowritten with 193 nm ArF excimer laser and characterized for their response to strain, temperature, bending, and torsion. These gratings couple light from the forward core mode to not only backward core mode but also backward rod modes. This results in multiple resonance peaks in the reflection spectrum. All resonance wavelengths exhibited the same temperature and strain response with coefficient similar to that of Bragg gratings in standard single-mode fiber. The strength of the resonance peaks corresponding to the backward rod modes showed high sensitivity to bending and torsion. 相似文献
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光子晶体纤维一般为用石英玻璃制作的有孔纤维,它们在3μm~20μm的中红外和远红外光谱范围内是不透明的。最近,以色列Tel-Aviv大学的研究人员利用卤化银(AgClxBr1-x)晶体材料制作出了在上述光谱范围内高度透明的新颖光子晶体纤维。这种光子晶体纤维由两种固体材料构成:其芯为纯AgBr(n=2.16),包层为AgCl(n=1.98)。研究人员对已制成的外径为1mm、长度约为1m的这种软性光子晶体纤维进行了测试。结果表明,其性能与理论模拟非常一致。这种新颖的卤化银光子晶体纤维对于红外激光功率传输、红外辐射测量以及红外光谱学都是极其有用的。 相似文献
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非线性变折射率纤维透镜理论 总被引:1,自引:0,他引:1
本文对非线性变折射率纤维透镜进行了分析,利用高斯光束在非线性变折射率纤维中传播的稳态自聚焦理论以及在线性介质中传播的ABCD定律,导出了计算这种透镜的焦距及束腰半径的解析表达式。 相似文献
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1 纤维喉镜检查前的准备1 1 检查单的准备 :认真核查部位和要求 ,并向患者说明注意事项。1 2 检查前常规注射 0 5mg的阿托品 ,以减少咽喉部的分泌物 ,先于两侧鼻腔喷雾 3%麻黄素液一次 ,收缩鼻粘膜以扩大鼻腔视野 ,有利于鼻腔分泌物的排除。再用 1%的地卡因液喷雾两侧鼻腔 ,以减轻纤维喉镜体通过鼻腔时所带的不适感 ,将舌伸出口腔外 ,一手用无菌纱布包裹人舌的前端 ,另一手持1%地卡因喷雾器 ,将药液均匀地喷入咽腔和喉腔 ,同时嘱病人发“衣”的声音 ,以利于药物有效地喷入咽喉腔粘膜 ,达到良好的麻醉效果 ,3~ 4次喷药后可行纤维喉镜… 相似文献
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气道隆起性病变,是呼吸系统的常见病,如中心型肺癌、炎性肉芽肿等等,我们应用Nd~(3+):YAG激光治疗气道隆起性病变56例,有效率100%,现报道如下: 资料与方法一般资料: 56例中,男性40例,女性16例。最小年龄19岁,最大年龄80岁。全部病例均经纤维支气管镜(简称纤支镜)检查活检,病理组织学确诊。其中鳞状细胞癌38例,炎性肉芽肿17 相似文献
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Hwa-Yaw Tam 《中国电子科技》2008,6(4):434-437
An intensity-modulated, fiber Bragg grating (FBG) sensor system based on radio-frequency (RF) signal measurement is presented. The RF signal is generated at a photodetector by two modulated optical signals reflected from the sensing FBG and a reference one. Bragg wavelength shift of the sensing FBG changes intensity of the RF signal by changing phase difference between the two optical signals, with temperature effect being compensated automatically by the reference FBG, Strain measurement with a maximum sensitivity of -0.34 μV/με has been achieved. 相似文献
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用于场发射显示的大面积碳纳米纤维阴极 总被引:1,自引:1,他引:0
XinheTang ErnstHammel KlausMauthner MarkusTrampert PaulDeeben EdwardCosman BoikeKropman KeesKortekaas DanieldenEngelsen 《现代显示》2004,(3):40-44
目前我们已经开发了用于场发射显示的碳纳米管发射体制作工艺。该工艺有希望被用于在玻璃衬底上制作大面积碳纳米管阴极,而且还可以在低于玻璃熔化点的条件下定位生长碳纳米管。在一个8×8 cm2的试验件上,展示了全部象素的特性。测试表明,在电场强度为1.79V/μm的条件下,可提供0.9mA/cm2的电流密度;在4.25V/μm的情况下可高达2.7 mA/cm2的电流密度。进而成功地同比放大制成16in阴极。我们期望所制成的大面积碳纳米管阴极,能用于32in、60in或更大面积的场发射显示器。 相似文献
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1 纤维喉镜检查前的准备1 1 检查单的准备 :认真核查部位和要求 ,并向患者说明注意事项。1 2 检查前常规注射 0 5mg的阿托品 ,以减少咽喉部的分泌物 ,先于两侧鼻腔喷雾 3%麻黄素液一次 ,收缩鼻粘膜以扩大鼻腔视野 ,有利于鼻腔分泌物的排除。再用 1%的地卡因液喷雾两侧鼻腔 ,以减轻纤维喉镜体通过鼻腔时所带的不适感 ,将舌伸出口腔外 ,一手用无菌纱布包裹人舌的前端 ,另一手持1%地卡因喷雾器 ,将药液均匀地喷入咽腔和喉腔 ,同时嘱病人发“衣”的声音 ,以利于药物有效地喷入咽喉腔粘膜 ,达到良好的麻醉效果 ,3~ 4次喷药后可行纤维喉镜… 相似文献