密集波分复用条件下的光轨网络串扰分析与仿真

光轨网络是一种能够利用成熟的光学器件实现带宽灵活分配和信息交换的新型网络.串扰是限制光轨网络的物理层性能及其扩展性的重要因素.本文讨论了典型的光轨网络节点中异频串扰和同频串扰的产生原因,理论分析了两者对光轨网络的物理层传输性能的影响.给出了3种串扰性能的评价方法.以密集波分复用技术为应用背景,分别搭建了器件隔离度为20 dB和30 dB的、具有3个节点5个波长且单波长速率为2.5 Gbps的光轨网络,仿真了串扰在光轨网络中的传播过程,并计算了光轨网络的误码率、功率代价和相对串扰.理论分析和仿真结果表明:光滤波器、解复用器和复用器是光轨网络中串扰产生的关键器件,且提高器件的隔离度等性能对于提高光轨网络的传输性能会有较显著的效果;在密集波分复用条件下,串扰对单波长速率为2.5 Gbps的光轨网络的误码率和功率代价具有显著的影响,从而限制了光轨网络实际可用的节点数目.     

High-gain composite microstrip patch antenna with the near-zero-refractive-index metamaterial

A high-gain rectangular microstrip patch antenna which is covered by a single layer metamaterial (MTM) superstrate with the near zero refractive index is proposed. The refraction of the metamaterial at frequency 3.51 GHz–3.57 GHz is very close to zero. The metamaterial with the near zero refractive index is placed 42 mm above an ordinary rectangular microstrip patch antenna. The effectively zero refractive index behavior of metamaterial superstrate can gather the wave emitted from the microstrip patch antenna and collimate it toward the normal direction of the antenna. The finite element method (FEM) and the finite difference time domain (FDTD) method are used to study the characteristics of this antenna. The results of the two methods indicate that the realized gain of the proposed antenna is increased by more than 6 dB, and the antenna has a flatness high gain in the predicted frequency band, where the proposed MTM is designed to have a near zero index of refraction. Therefore, the high-gain antenna is effectively enhanced based on the near-zero-refractive-index metamaterial.     

An efficient catalyst for ring opening of epoxides with phenol and thiophenol under solvent-free conditions

An efficient and rapid procedure for ring opening reaction of various epoxides with phenol and thiophenol derivatives was developed. The procedure can be obtained at room temperature under solvent-free condition in presence of (C₄H₁₂N₂)₂[BiCl₆]Cl·H₂O (1 mol %). This catalyst can be reused several times without significant loss of activity.     

高铁低铝煤矸石酸浸除铁及其废液利用的研究

研究以六盘水盘县某矿区煤矸石为原料,采用单因素试验和正交试验的方法,研究了酸浸法除铁的工艺。通过对酸浓度、酸浸温度、酸浸时间、液固比四个影响因素的考察,得到各因素对酸浸除铁的影响规律。通过正交试验,确定了除铁的最佳工艺条件为:酸浓度15%、酸浸温度45℃、酸浸时间4h、液固比4:1,在此条件下的除铁率为90.3%。并用酸浸液制备了符合国家相关标准的氧化铁红产品。