Analysis and computation of ESI coefficient of planar waveguide based on field matching

首次采用了场的最小二乘方 (LSE)和最小均方误差 (LMS)判据寻找平板波导的等效阶跃折射率 (ESI)模型 ,并通过它预测了平板波导的传输特性。计算结果表明 ,原始波导与等效波导场分布在具有最大近似性的基础上 ,ESI模型可以在一定范围内有效的预测平板波导的传输特性。归一化频率与第一个高阶模的截止频率之比在小于 0 7的情况下 ,用上述两种判据找到的ESI模型预测传输常数相对误差小于 0 0 1 % ,预测归一化传输常数的相对误差小于 1 0 %。A method to find Effective Step-Index(ESI) model based on field matching criter ia of least-square-error(LSE) and least-mean-square(LMS) error is put forward, and the propagation quality from ESI coefficients is predicted. When the ESI model a n d the original waveguide have the best approximated field distribution, the prop agation quality of planar waveguide efficiently can be predicted based on ESI mo del in specific range. When the ratio between normalized frequency and cut-off fre quency of the first higher model is lower than 0.7, the relative error of predic t ing propagation constant from the ESI model is less than 0.01%, and the relative error of predictiong normalized propagation constant is less than 10%

Application and Improvement of Finite-difference Time-domain Algorithm in the Analyses of Optical Waveguide

对时域有限差分算法在弱导光纤中应用时吸收边界条件的设置和计算结果的误差进行了讨论 ,并提出改善计算精度的方法。文中给出用这种方法计算普通光纤传输特性的结果In this paper,we discuss the application of CFDTD (Cylindrical Finite Difference Time Domain)algorithm in the analyses of weak guide optical fiber.Especially,the setting of the absorbing boundary condition and the error of the result are discussed.We present a way to improve the accuracy of the algorithm.Finally,the propagation characters of optical fiber are given in the paper

Post-trauma Mental Health Problem among 8~14 Year Old Children and Its Risk Factors One Year after Sichuan Earthquake in Mianyang

目的:探讨BDNF Val66Met基因多态性与温暖的教养方式对青少年抑郁水平的影响。方法:采用爱荷华青年和家庭项目(Iowa Youth and Families Project)中教养问卷的温暖维度与儿童抑郁自评量表(Children’s Depression Inventory,CDI)分别对838名青少年抑郁症状与父母的教养方式进行测量,在确定被试BDNF Val66Met基因型后,用多重线性回归对测得数据进行分析。结果:温暖的家庭教养方式与青少年抑郁症状负相关;BDNF Val66Met多态性与青少年抑郁症状无显著相关;BDNF Val66Met多态性与温暖的家庭教养方式的交互作用显..

基于光纤Bragg光栅的滤波技术

介绍了国际上最新的基于光纤Bragg光栅的光纤滤波技术的发展情况,详细阐述了分布反馈式光纤Bragg光栅滤波器、多波长选择光纤Bragg光栅滤波器、应用光纤Bragg光栅的Michelson干涉型(MI)滤波器以及光纤Bragg光栅滤波耦合器的理论难点、基本原理及其应用

应用新型双T选频网络的OFCS光检测放大器

介绍了一种新型用于OFCS（光纤电流传感器）的PIN光检测放大器的设计，并提出了一种新型的双T型选频网络电路，对放大器各级的设计原理进行了详细的理论分析。理论与实践都证明这种新型光检测放大器信噪比较高，能对微弱的PIN光信号进行有效的检测和放大

新型光纤的技术发展及应用

文章介绍了国际上最新的通信光纤的技术发展情况,包括新型多模光纤、单模光纤的制造技术及其应用,还详细地介绍了国内外最新类型的特种光纤及其发展、应用。此外,对我国光通信的技术现状、发展和趋势也进行了一定程度的阐述

Technology of Filters Based on Fiber Bragg Gratings

介绍了国际上最新的基于光纤Bragg光栅的光纤滤波技术发展情况,详细阐述了分布反馈式光纤Bragg光栅滤波器、多波长选择光纤Bragg光栅滤波器、应用光纤Bragg光栅的Michelson干涉型（MI）滤波器以及光纤Bragg光栅滤波耦合器的理论难点、基本原理及其应用。The paper introduces the latest technical development of band-pass filters based on fiber Bragg gratings.The major theoretical principle,as well as application of Distributed feed back FBG filters, multewavelength selectieve FBG filters, Michelson interferometer band-pass filters and in-coupler Bragg grating filters are elaborated in details

Technical Development and Application of Novel Optical Fiber

介绍了国际上最新的通信光纤技术发展情况 ,包括新型多模光纤、单模光纤的制造技术及其应用。文章还详细地介绍了国内外最新类型的特种光纤及其发展、应用。此外 ,对我国光通信的技术现状、发展和趋势也作了一定程度的阐述The paper introduces the latest technical development of communication fiber, including the manufacturing technology and application of novel multimode optical fiber and single mode optical fiber. The development and application of the latest special optical fiber are also presented in details, moreover, the domestic present situation and developing trend of fiberoptic communication are described to certain degree

Analysis and Design of a Novel Photodetector Amplifier Used for FOCS

介绍了一种新型应用于 FOCS (光纤电流传感器 )的 PIN光检测放大器的设计 ,并提出了一种新型的双 T型选频网络电路 ,对放大器各级的设计原理也进行了详细的理论分析。理论与实践都证明这种新型光检测放大器信噪比较高 ,能对微弱的 PIN光信号进行有效地检测和放大A novel PIN photo-detector amplifier used for FOCS (fiber-optic current sensor) is presented amd a new dual T-type frequency selecting network is also proposed The principles of design are analyzed in details Experimental results show that a high SNR is obtained and a weak signal can be detected and amplified effectively国家自然科学基金资助项目!编号 (6 97770 12

田菁根瘤菌YIC4027可溶性趋化受体Tlp1的功能鉴定

【目的】初步探究田菁根瘤菌Sinorhizobium alkalisoli YIC4027中唯一含有PAS结构域可溶性趋化受体Tlp1的功能机理。【方法】本研究基于Red重组系统以及三亲接合技术进行缺失突变株的构建。对野生型和突变株的生长情况、趋化能力、趋氧性、细胞凝结、生物膜的形成、胞外多糖产量、在宿主根表的定殖及竞争性结瘤等表型进行了测定。【结果】与野生型相比,突变株的生长不受影响,趋化和趋氧能力降低,在宿主根表的定殖及竞争性结瘤能力降低,而细胞凝结能力、生物膜形成以及胞外多糖产生能力等均有所提高。【结论】本研究首次证实了S. alkalisoli YIC4027中可溶性趋化受体Tlp1影响细胞的趋化运动