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951.
Wiesł Nizioł 《Compositio Mathematica》2001,129(2):123-147
We define and study a candidate for 'arithmetic' cohomology theory with values in crystalline p-adic smooth sheaves. We show that it injects into arithmetic étale cohomology and prove a duality result. 相似文献
952.
953.
《Particuology》2023
The efficiencies of the diffusion deposition of nanoaerosols for a single fiber for the models of aerosol filter and wire mesh screen are studied numerically in the extended range of the Peclet number Pe. The rectangular periodic cell model for fluid flow and convective-diffusive transport of small aerosol particles is used. Most of the previous theoretical and experimental studies of single fiber diffusion deposition efficiency were for the case of Pe > 1. The array with uniform square or chess grid of fibers and of a row of circular cylindrical fibers are considered as the filter and wire mesh screen models. The flow and particles transport equations are solved numerically using the Boundary Element Method.The obtained numerical data are used to derive the approximate formulas for the deposition efficiency in the entire range of the Peclet number for the various porosities of the filter medium or distances between fibers in a wire mesh screen. The derived dependencies take into account nonlinearity of the deposition efficiency at the low Peclet numbers. The obtained analytical dependencies compare well with the numerical and experimental data. 相似文献
954.
955.
956.
高精度动态光纤应变传感研究 总被引:1,自引:0,他引:1
传统的光纤应变传感技术无法在满足高精度和强环境适应性的同时实现稳定的动态应变传感.为了解决该问题,本文将光干涉原理应用于光纤应变传感,设计了一种强环境适应性的基于干涉结构的高精度光纤应变传感系统,基于扫频干涉信号的互相关系数,该系统可以稳定地探测应变.本文还提出一种动态探测算法,该算法弥补了系统只能探测较小应变的缺陷,大大提升了实际应变的探测范围,同时还实现了动态的应变检测;采用三次样条插值算法,提升了小应变探测的精度.理论分析和仿真模拟表明,在加入白噪声的信号信噪比为15dB时,插值后的探测精度是未插值探测精度的2.3倍,插值后本系统探测结果的最大误差只有约9nε. 相似文献
957.
Ultra-broadband polarization splitter based on graphene layer-filled dual-core photonic crystal fiber 下载免费PDF全文
An ultra-broadband polarization splitter based on graphene layer-filled dual-core photonic crystal fiber(GDC-PCF)that can work in a wavelength range from 1120 nm to 1730 nm is proposed in this paper. Through optimizing fiber configuration, the polarization splitter has an extinction ratio of-56.3 dB at 1.55 μm with a fiber length of 4.8 mm.Compared with the photonic crystal fiber reported splitters, to our knowledge, the GDC-PCF splitter with the extinction ratio below-20 dB has a super wide bandwidth of 610 nm. Due to the excellent splitting characteristics, the GDC-PCF will be used in coherent optical communication systems in a wavelength range from infrared to mid-infraed. 相似文献
958.
An experiment on gain enhancement in the long wavelength band erbium-doped fiber amplifier (L-band EDFA) is demonstrated using
dual forward pumping scheme in double-pass system. Compared to a single-stage single-pass scheme, the small signal gain for
1580 nm signal can be improved by 13.5 dB. However, a noise figure penalty of 2.9 dB was obtained due to the backward C-band
ASE from second stage and the already amplified signal from the first pass that extracting energy from the forward C-band
ASE. The maximum gain improvement of 13.7 dB was obtained at a signal wavelength of 1588 nm while signal and total pump powers
were fixed at -30 dBm and 92 mW, respectively. 相似文献
959.
一种通带平坦的粗波分复用/解复用器件的研制 总被引:3,自引:4,他引:3
随着粗波分复用(CWDM)系统在城域网和接入网中日益广泛的应用,人们对粗波分复用/解复用器的研究也逐渐展开。报道了一种8通道波长间隔为20nm的粗复用/解复用器。该器件基于阵列波导光栅(AWG)原理设计,利用平面光波导技术(PLC)制作,采用多模干涉输入结构和“S”形阵列波导结构,实现了较宽的通带宽度和较低的串扰。实验测得1dB带宽大于10nm,相邻串扰大于24dB,非相邻串扰大于32dB。介绍了其设计原理和制作过程,给出了光束传播法(BPM)数值模拟结果,并和实验结果进行了对比。 相似文献
960.
We review our recent work in the implementation of optical single-sideband (OSSB) modulation and in the application of this modulation format to microwave photonics and optical testing systems. We have developed an enhanced OSSB modulator for wide-band operation, the so-called bidirectional OSSB modulator, and a simplification of this scheme for narrow-band applications. These OSSB modulators are based on the use of a standard single-electrode Mach-Zehnder electro-optic modulator (MZ-EOM) and passive fiber-optic components. In both designs, the OSSB operation is shown to be independent of the MZ-EOM bias. Therefore, the optical modulation depth at the output of the device can be enhanced using minimum transmission biasing to provide suppression of the optical carrier. Finally, we demonstrate the application of OSSB modulators to the improvement of microwave/millimeter-wave subcarrier multiplexing fiber-optic links and to narrow-band fiber radio systems. In addition, we analyzed the feasibility and the limitations of an optical vector network analysis technique based on OSSB modulation that can provide sub-picometer wavelength resolution. 相似文献