A novel control method for on-off gain and gain tilt of fiber Raman amplifiers

Considering spectrum tilt due to signal-to-signal Raman scattering (SSRS) in backward distributed fiber Raman amplifiers (B-DFRA),an inverse tilted on-off gain profile is adopted to achieve flat net gain.A simple approximate linear relationship of pump power at each wavelength versus on-off gain level and tilt was derived numerically and experimentally so that a novel control method was established.Since there are only 3 pre-determinable constants required for individual pump wave,it is easy to be realized.As an example,maximum errors less than 0.2 and 0.4 dB respectively for average gain and gain tilt were achieved over C+L band in 100-km back-pumped standard single-mode fiber (SMF) experimentally.     

有机废气的生物膜净化过程

低浓度有机废气的生物膜净化过程主要通过把废气从气相转移到液相或固相表面的液膜中,然后利用微生物降解液相或固相表面液膜中的污染物.自养菌和异养菌组成的复合菌在填料塔上的挂膜过程经历吸附、菌体增殖、生物膜初步形成、生物膜成熟四个阶段,最终开始发挥作用.     

右转常绿信号交叉口短右转车道通行能力研究

为了估算右转常绿信号交叉口短右转车道通行能力,应用概率论相关方法,将右转车辆到达直行、右转共用车道的情况分成右转车辆被直行车阻挡、右转车辆溢出后被直行车辆阻挡和没有被阻挡三种情况.提出前两种情况发生的概率模型及均值模型,第三种情况的概率及通行能力,以此为基础建立出短右转车道的通行能力计算模型.用福州市信号交叉口实测数据对模型进行标定,应用VISSIM仿真软件验证模型.结果表明,右转车道通行能力随着短右转车道长度的增加而增大,车道长度越长,通行能力增长的趋势越缓.模型能较好的反映短右转车道对右转车道通行能力影响的实际情况,可为短右转车道设置提供理论依据.     

铜基形状记忆合金相组织形态的SEM研究

对铜基形状记忆合金的相变过程和显微形态进行观察,就不同介质和不同温度的淬火处理对相组织显微形态的影响进行了初步探讨。     

47-wavelength flat erbium-doped fiber ring laser with reduced operation power

Multi-wavelength laser generated in a piece of erbium- doped fiber (EDF) is attractive because of its high gain and high efficiency with simple structure, which is very useful in wavelength division multiplexing (WDM) sys- tems or fiber sensors. However, the EDF faces a big problem of intrinsic homogeneous line broadening[1] that prevents multi-wavelength oscillation at room tempera- ture. Yamashita et al.[2] have placed the EDF into liquid nitrogen (77 K) to reduce the homogeneous line w…     

三段式带通型可调谐全光纤声光滤波器

为克服基于普通单模光纤的声光效应只能实现带阻滤波器的问题 ,提出并实现了一种三段式结构的全光纤带通型可调谐声光滤波器。该文分析了三段式结构实现带通滤波的原理 ,考虑声波的衰减而优化了第一段和第三段光纤的长度比 ,并且指出中间段光纤的长度对于滤波器消光比的影响。这种新型结构的滤波器与以往的全光纤滤波器相比 ,边带抑制比高 ,没有移频现象 ,适合于高速波分复用系统的应用     

硫代米蚩酮-吐温-80显色体系-卡尔曼滤波光度法同时测定金和银

在pH3.5的HAc-NaAc缓冲介质中,在表面活性剂Tween-80存在下,金和银与硫代米蚩酮(TMK)形成胶溶配合物,0～11μg/25mL的Au和0～7μg/25mL的Ag符合比尔定律。用卡尔曼滤波光度法进行测定和微机处理。对合成样测定结果,Au平均回收率为97.2%,Ag平均回收率为98.5%。     

高峰期内的公交服务可靠度研究

在分析高峰期内道路交通现状和高峰客流特点的基础上,从可靠度理论的角度,对乘客在车内的拥挤成本、由于等车产生的时间延误惩罚成本等进行了分析,建立了高峰期内公共交通系统服务可靠度的模型,是评价公交服务能力的一种有效方法.     

Effective generation of optical quadruple frequency millimeter-wave based on fiber laser using injection rational harmonic mode-locked technique

A method to generate the optical quadruple frequency millimeter-wave with high power efficiency is pro- posed and demonstrated based on the combination of the injection 2nd-order rational harmonic mode- locked fiber ring laser technique and the fiber grating notch filter. In this approach, the fiber Bragg grating notch filter is inserted into the laser cavity to prevent the undesired optical carrier, so that the pump power can be converted to 2nd-order harmonic wave more efficiently. In our experiment, the power efficiency of optical quadruple frequency millimeter-wave （40 GHz） generation is ten folds of that of our previous method based only on the rational harmonic mode-locked technique.     

导电沥青混凝土的机敏特性

采用间接拉伸疲劳试验对圆柱体试件的机敏特性进行探讨;通过受拉时的疲劳特性与电性能的对应关系,由电学性能逆推疲劳寿命,实现健康状况自诊断.研究结果表明:导电沥青混凝土能够有效地对其自身在加载过程中产生的应变进行诊断,输出电阻随着应变的增加而可逆地增加,随着应变的减小而可逆地减小;导电沥青混凝土受压后,先后经历追密、稳定和破坏3个阶段,其输出电阻率也会发生相应变化,电阻率和内部结构之间存在一定响应关系;电阻率的变化与其内部的载流子浓度成反比,可据单位体积内载流子浓度的变化进行自诊断.