色散管理光纤激光器中类噪声脉冲的实验研究

Based on an erbium.doped dispersion-managed fiber laser,the characteristics of noise-like pulses under different net cavity group velocity dispersions (GVDs) are experimentally investigated.Results show that the spec-tral bandwidth of noise-like pulse will increase as the net cavity GVD increases and attains maximum when the GVD is slightly positive.The effect of Raman scattering is enhanced due to the temporal width attains minimum.When the net cavity GVD increases continually and further into the positive region, the spectral width begins to decrease and the effect of Raman scattering is suppressed due to the positive dispersion.Our experimental results are in good agreement with the previous prediction of numerical simulation.     

基于非线性偏振旋转的可调谐多波长掺铒光纤激光器

实现了一种基于非线性偏振旋转(NPR)的可调谐多波长掺铒光纤(EDF)激光器.偏振相关隔离器和保偏光纤(PMF)是激光器的关键组件.非线性偏振旋转会引起腔体的自滤波和光强的峰值限制效应,从而能有效地减弱掺铒光纤均匀加宽所造成的强烈模式竞争,形成稳定的常温多波长振荡.腔损耗的色散特性使激光输出波长在5 am内可连续调谐.由于激光腔的自滤波周期由腔内双折射强度决定,也可以通过改变保偏光纤的有效长度来实现.当用两段保偏光纤和偏振控制器组合后,实验中得到了间隔为0.25 nm和0.75 nm可调谐的稳定多波长振荡.     

Space-frequency-Doppler coded OFDM over the time-varying Doppler fading channels

In this paper, space-frequency-Doppler coded OFDM (SFDO-OFDM) scheme over the time-varying Doppler fading channels via the time-frequency duality is proposed. Based on the basis expansion model (BEM) and the time-frequency duality, through the circulant matrix diagonalized processing, the nonlinear time-varying Doppler fading channel is dually converted to the virtual frequency-selective linear channels. With OFDM module, subgrouping the subcarriers in OFDM through the block matrix method and fatherly general complex orthogonal coding (GCOD) on each corresponding block subcarriers, SFDO-OFDM codes for the general multiple input multiple output (MIMO) is thus constructed. And concatenating it with the signal constellation precoding, full maximum diversity gains including the inherent Doppler fading are achieved. Theoretical analysis and corroborating simulation results demonstrate that, comparing with existing Doppler coding alternatives, the proposed scheme can effectively and robustly combat the Doppler fading with high bandwidth efficiency and even lower bit error ratio (BER).     

WCDMA和GSM1800宏蜂窝共基站干扰分析

本文根据GSM1800和WCDMA协议,通过计算机仿真和确定性计算方法,重点对WCDMA系统与GSM1800系统在基站共站情况下进行干扰分析.     

色散缓变光纤中Raman孤子自频移效应的研究

利用绝热扰动法研究了色散缓变光纤中Ｒａｍａｎ孤子自频移效应，得到了色散缓变光纤中Ｒａｍａｎ孤子自频移的表达式。结果表明：光纤色散变化率存在一个可以有效抑制孤子自频移的阈值，当光纤色散变化率大于这个阈值时，色散缓变光纤可以抑制孤子自频移，而当光纤色散变化率小于这个阈值时，色散缓变光纤不仅不能抑制孤子自频移，反而加剧孤子自频移。     

Experimental Study of Oilfield Water Plugging with Organic Chromium Gel

Chemistry and Technology of Fuels and Oils - Application of water flooding technologies in the oilfield causes intensive heterogeneity of the oil reservoir and improper circulation of the injected...     

自由电子激光的小型化研究

本文通过对自由电子激光输出波长的分析,指出了自由电子激光小型化的研究方向─-微型摆动器的研究。在分析了小周期摆动器研究现状的基础上,提出了电流摆动器。它不但具有与静磁摆动器相同的效果,而且它的周期可以任意调节。因而,它便于控制。最后,还指出了有待进一步研究的问题。     

一种新型的单边带调制技术

从理论和实验两方面研究了一种新型单边带调制(SSB)技术,通过在中心站合适设置单臂强度调制器的偏置电压,使调制器产生的奇数边带被抑制,采用滤波器滤除其中的一个二阶边带,即可产生单边带信号.用该新型的单边带调制技术产生的光毫米波理论上可以传输148 km.同时搭建了实验系统,采用10 GHz的本振信号源与2.5 Gbit/s的数字信号混频后驱动单臂强度调制器产生抑制奇数边带的调制信号,再通过一个滤波器得到20 GHz的单边带毫米波,还得到了不同载波边带比(CSR)情况下的毫米波眼图.通过实验分析不同载波边带比对传输性能的影响,发现载波边带比为0 dB时,传输性能最佳.     

环保型白油基钻井液研究和应用进展

白油为基液的环保型油基钻井液有助于解决井壁坍塌问题。本文介绍了环保型白油基钻井液在水平井、高温深井、大位移定向井、深水井及复杂地层钻探中应用现状,并提出了环保型白油基钻井液面临的问题及今后的研究方向,以期为国内钻井液技术的发展提供参考。     

随动式动态混合器掺稀混合性能研究

针对稠油掺稀过程中原混合器混合效果不佳的问题,选择满面式螺旋叶片作为混合元件,增加动力叶轮,以增强叶片对流体的剪切能力和转动频率.基于CFD仿真软件,对影响动态混合器混合效果的叶片螺距和动力叶轮两参数进行数值模拟分析,并以管内稀油体积分布情况作为评价标准,研究混合过程中混合元件几何结构的变化对混合器性能的影响规律.结果...