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1.
A discrimination measurement method and demodulation technique for fiber Bragg grating （FBG） sensors were presented using digital filtering technique. The system can control a tunable fiber Fabry-Perot filter with sawtooth wave voltage generated by digital clock to interrogate FBG sensors. Using the analogue digital converter （ADC）, the reflected FBG signals were sampled with synchronous digital clock. With the aid of digital matched filtering technique, the sampled FBG signals were processed to obtain the maximum signal-to-noise ratio （SNR） and the Bragg wavelength shift from the FBG signals was recovered. The results demonstrate that this system has a scanning range of 1 520 nm-1 575 nm,and the wavelength detection accuracy is less than 2 pm with 1.5 Hz scanning frequency. 相似文献
2.
提出了一种基于由热扩芯光纤构成的马赫-曾德干涉滤波器的新型多波长可调谐环形腔掺铒光纤激光器.马赫-曾德干涉滤波器由一段掺镱光纤和两根实验室自制的热扩芯光纤熔接而成.当马赫-曾德干涉滤波器中的掺镱光纤受到980 nm激光二极管泵浦时,滤波器的干涉条纹将向长波长方向漂移.利用该可调谐滤波器构建一个环形腔掺铒光纤激光器,获得了11个激射波长同时输出,每个激射波长的信噪比都超过40 dB.通过改变掺镱光纤的泵浦功率,激光器的激射波长可调. 相似文献
3.
4.
A novel quantum dots (QDs) optical fiber amplifier was proposed and demonstrated. It was fabricated by dipcoating the PbSe
QDs doped sol onto the taper region of fiber coupler. The PbSe QDs was synthesized according to a colloidal method. A lower
refractive index sol was also synthesized as the host of PbSe QDs. A standard single mode fiber was used to make the fusion
tapered fiber coupler which had double input and output ports. With the simple structure, a signal and a pump can be injected
into the amplifier and excite the PbSe QDs through evanescent wave. The experimental results indicated that the amplified
light wave was observed at 1 550 nm wavelength with 980 nm wavelength laser diode as pump. 相似文献
5.
In this study, supported nonmetal （boron） doping TiO2 coating photocatalysts were prepared by chemical vapor deposition （CVD） to enhance the activity under visible light irradiation and avoid the recovering of TiO2. Boron atoms were successfully doped into the lattice of TiO2 through CVD, as evidenced from XPS analysis. B-doped TiO2 coating catalysts showed drastic and strong absorption in the visible light range with a red shift in the band gap transition. This novel B-TiO2 coating photocatalyst showed higher photocatalytic activity in methyl orange degradation under visible light irradiation than that of the pure TiO2 photocatalyst. 相似文献
6.
Proteomic analysis of human umbilical vein endothelial cells exposed to PM<Subscript>2.5</Subscript>
Ji Zhu Lin-wen-si Zhu Jin-huan Yang Ying-ling Xu Cui Wang Zhuo-yu Li Wei Mao De-zhao Lu 《Journal of Zhejiang University. Science. B》2018,19(6):458-470
Exposure to fine ambient particulate matter (PM2.5) is known to be associated with cardiovascular disease. To uncover the molecular mechanisms involved in cardiovascular toxicity of PM2.5, we investigated alterations in the protein profile of human umbilical vein endothelial cells (HUVECs) treated with PM2.5 using two-dimensional electrophoresis in conjunction with mass spectrometry (MS). A total of 31 protein spots were selected as differentially expressed proteins and identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS. The results demonstrated that DNA damage and cell apoptosis are important factors contributing to PM2.5-mediated toxicity in HUVECs. It is further proposed that PM2.5 can inhibit superoxide dismutase (SOD) activity and increase reactive oxygen species (ROS) and malonaldehyde (MDA) production in a concentration-dependent manner. Induction of apoptosis and DNA damage through oxidative stress pathways may be one of the key toxicological events occurring in HUVECs under PM2.5 stress. These results indicated that the toxic mechanisms of PM2.5 on cardiovascular disease are related to endothelial dysfunction. 相似文献
7.
光学调谐技术在光纤光栅传感器中的应用 总被引：1，自引：0，他引：1
邓勇 《南通职业大学学报》2002,16(2):22-26
光纤光栅传感器是最近十年发展起来的一种新型光纤传感器,可用于应变（力）、温度、压力、液位的测量,与传统光纤传感器相比有许多优点。光纤光栅传感器的核心技术是光学调谐技术。目前,国外常用的调谐方法有:参考光纤光栅反射波长调谐匹配法、法布里-百洛透射波长调谐匹配法、激光源波长调谐匹配法、傅立叶变换先纤光谱仪法、马赫-曾德干涉仪信号读出法。本文对光纤光栅传感器的原理和应用等做了简述,并着重对各种先学调谐方法作了详细综述。 相似文献
8.
相位模板技术与布拉格光纤光栅的写入 总被引：4，自引：0，他引：4
由于相位模板法仅使用一个光学器件 ,因而减少了光纤光栅制造系统的复杂性 ,是光纤布拉格光栅写入法中最有前途、使用最广泛并且具有本征稳定性的一种方法 .本文总结了相位模板技术及各种光纤布拉格光栅的写入 .值得注意的是在相位干涉法中 ,只用一块相位模板 ,就可以调整写入光纤布拉格光栅的波长 .在这些系统中 ,写入光纤光栅的紫外线 ( UV )干涉条纹经由一些光学元件 ,其中 ,相位模板的作用通常是± 1级衍射光的分束器 相似文献
9.
In order to design birefringent holey fiber with beat-length independent of wavelength, an asymmetric structure is introduced to reduce its wavelength-sensitivity. The influence of structural parameters on the modal birefringence is calculated and analyzed. After optimizing the parameters, a flat dispersion curve of beat-length is obtained. The beat-length changes from 89.8 mm to 91.0 mm in wavelength range from 1.1 μm, to 1.7 μm, and its relative variation is 1.38%. If this fiber is made into zero-order qu... 相似文献
10.
An ecofriendly heterogeneous polyoxometalate (POM)-gold catalyst Au/BW11/Al2O3 was synthesized and used for solvent-free epoxidation of cyclooctene under mild reaction conditions using molecular oxygen as an oxidant and t-butyl hydroperoxide (TBHP) as an initiator. The catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), induced coupled plasma optical emission spectrometry (ICP-OES), and Brunauer-Emmett-Teller (BET). The catalyst showed good conversion and high selectivity without use of solvents or environmentally harmful oxidants. Moreover, the catalyst is recyclable up to three cycles with no significant loss in selectivity towards epoxide. 相似文献
11.
多波长泵浦拉曼光纤放大器增益最大化研究 总被引：1，自引：0，他引：1
应用遗传算法，对多波长泵浦的拉曼光纤放大器的增益最大化进行了研究．结果表明，当传输信号的波长、功率和信道数给定时，该算法能够给出增益接近最佳时的泵浦光的波长和泵浦能量的取值．对不同类型光纤的计算显示，单波长泵浦能获得较大增益的光纤，在多波长泵浦时不一定能获得较大增益．这为多波长泵浦的光纤拉曼放大器的设计提供了参考． 相似文献
12.
MBE growth of ZnSxSe1−x thin films on ITO coated glass substrates were carried out using ZnS and Se sources with the substrate temperature ranging
from 270°C to 330°C. The XRD σ/2σ spectra resulted from these films indicated that the as-grown polycrystalline ZnSxSe1−x thin films had a preferred orientation along the (111) planes. The evaluated crystal sizes as deduced from the FWHM of the
XRD layer peaks showed strong growth temperature dependence, with the optimized temperature being about 290 °C. Both AFM and
TEM measurements of these thin films also indicated a similar growth temperature dependence. High quality ZnSxSe1−x thin film grown at the optimized temperature had the smoothest surface with lowest RMS value of 1.2 nm and TEM cross-sectional
micrograph showing a well defined columnar structure.
Project supported by the National Science Council of PRC (No. 59910161981) and RGC grant from the Hong Kong Government under
Grant (No. NS-FC/HKUST 35) 相似文献
13.
α-diketones and β-diketones react with Grignard reagents in the presence of a catalytic amount of Cp2TiCl2 to yield α-ketols and corresponding ketones respectively. Sulfoxides can be deoxygenated by Cp2TiCl2/Al system. The possible mechanisms are also discussed.
Project (No. 20072033) supported by the National Natural Science Foundation of China and the Specialized Research Fund for
the Doctoral Program of Higher Education Ministry, China 相似文献
14.
TiO2/ ormosil planar waveguide was prepared by sol-gel method at low thermal treatment temperature （ 〈 200 ℃）. Scanning electron microscope, FT-IR spectrometer, spectrophotometer, atomic force microscopy, thermal analyzer, and dark m-line spectroscopy were used with the method of scattering-detection to investigate optical and structural properties. High optical quality waveguide film was obtained. The propagation loss of film was 0.569 dB/cm at a wavelength of 632.8 nm. 相似文献
15.
JIANG Xiao-yuan DU Feng ZHANG Xu JIA Yan-rong ZHENG Xiao-ming 《浙江大学学报(A卷英文版)》2007,8(11):1839-1845
Using SnxTi1-xO2 as carriers, CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide (CuO) were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 were examined using a microreactor-gas chromatography (GC) NO CO reaction system and the methods of BET (Brun- auer-Emmett-Teller), TG-DTA (themogravimetric and differential thermal analysis), X-ray diffraction (XRD) and H2-temperature programmed reduction (TPR). The results showed that NO conversions of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT (Brunauer, Deming, Deming and Teller) system and a typical mesoporous sample. There were two CuO diffraction peaks (2θ 35.5° and 38.7°), and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks (α, β and γ) from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the γ peak was the reduction of crystal phase copper oxide. In addition, a fourth peak (δ) of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive. 相似文献
16.
The chromatic dispersion( CD) degrades themodulation-phase relationships of lightwave signals,reducing information-carrying capacity through pulse-broadening in digital networks and distortion in analogsystems[1,2]. The widespread use of dense wavelengthd… 相似文献
17.
In an effort to find the effect of mass transfer ,surface tesion and drag forces on the velocity distribution,the mathematical model of the velocity profile of a nascent hollow fiber during membrane formation in the air gap region was numerically simulated by using the Runge-Kutta method (fourth-order method).The effect of mass transfer on velocity distribution based on the complicated function(G(Ch^s))was presented and the dffects of a complicated function were studied in two cases:in the first case,G(Ch^s) was constant;in the second,G(Ch^s) was variable.The latter was done by varying with the concentration of solvent in a nascent hollow fiber through the air-gap region.One empirical equation was used to describe this change and the predected values had a better agreement with the experimental values.To verify the moedl hypotheses,hollow fiber membranes were spun from 20:80 polybenzimidazole/polyetherimide dopes with 25.6 wt％ solid in N,N-dimethylacetamide (DMAc) using water as the external and internal coagulants.Based on the experimental results of dry-jet wet-spinning process for the fabrication of hollow fiber membranes,it is found that the model calculated values were in a good agreement with the experimental values. 相似文献
18.
Ml0.7Mm0.3Ni3.7Co0.7Mn0.4Al0.2 nanocrystalline hydrogen storage materials are prepared by melt-spinning(MS).X-ray diffraction is used for the measurement of the nanocrystalline size.Compared to the electrode of polycrystalline alloys,the property of activation MH9metal hydride)electrode of the alloys with nanometer scale became worse and the inital discharge capacity decreased.It may be ascribed to the decrease of the total amount of rare earth metals and the increase of oxygen on the surface from the analysis of components of the alloys.After heat-treatment,the electrochemical performance of MH electrode of as-spun alloys could be improved,which could be attributed to the alleviation of the lattice strain. 相似文献
19.
Surface morphologies of Zr52.5 Al10 Ni10 Cu15 Be12.5 bulk metallic glass after being rolled at both a temperature around T9 and near （ Tx - 50） K were investigated with a scanning electron microscopy. Macroscopic and microscopic observation results show that squamae, cracks, steps and wedges exist on the surface when the samples were rolled at temperatures around Ty. However, a smooth and fiat surface appears when the samples were rolled at temperatures near （ Tx - 50） K. These results indicate that the mode of deformation in the supercooled liquid region is a partially homogeneous flow at a temperature around T9, and a fully homogeneous one at temperatures near （ Tx - 50） K. According to the results, it is more feasible to roll the amorphous alloys at temperatures near （ Tx - 50） K to obtain parts with smooth and fiat surface. 相似文献