Optimum Design for RF-to-Optical Up-Converter in Coherent Optical OFDM Systems

In this letter, we conduct analysis on the optimum design for RF-to-optical up-converter in coherent optical OFDM systems using an optical I/Q modulator. We first derive closed-form expressions for the nonlinearity in the optical I/Q modulator, represented by two-tone intermodulation products as a function of the bias point and modulation index. Additionally, we perform a numerical simulation to identify Q-penalty and the excess modulation insertion loss under various transmitter conditions. We find that in contrast to the direct-detected system, the optimal modulator bias point for the coherent system is pi, where the Q-penalty and excess loss are minimized     

拉伸试验测量不确定度的研究

分析了拉伸试验中抗拉强度Rm的影响因素，对测量不确定度的主要分量进行量化，评定了Rm的相对测量不确定度，作为生产检验中评定测量不确定度的尝试，以便为用户提供钢材性能测量结果的不确定度。     

炼钢中间包塞棒液压伺服比例控制系统的应用

济钢第三炼钢厂中间包塞棒液压伺服比例控制系统采用伺服比例阀和伺服缸等,系统设计完善,功能齐全,可实现塞棒位置的闭环控制,保证了结晶器中钢水液面的稳定。     

An alternative method to compute the component fractions in the geometrical optical model: visual computing method

A method called visual computing was used to solve angular four-components' proportions and directional vegetation cover fraction for discrete canopies and continuous row-planted plants. It proved effective to predict the angular characteristics on pixel scale. The method could be an alternative way to a classical solution of geometrical optical models. A visual computing method would be effective especially when the canopies' spatial distribution and shapes were irregular and could not be described statistically.     

A broadband PHEMT MMIC distributed doubler using high-pass drain line topology

A broadband frequency doubler, based on distributed amplifier techniques, has been designed to operate from 11 to 21 GHz. In order to reject the fundamental signal over a broadband frequency range, the conventional low-pass drain line structure was replaced with the high-pass structure. This topology can suppress fundamental signals over broadband without any balanced structure so that the chip size can be more compact. Measured conversion losses of better than 10 dB from 11 to 21 GHz input frequencies are achieved with fundamental signal rejection better than 12 dB. To the best of our knowledge, this is the first demonstration of distributed doubler using the high-pass drain line topology.     

视觉诱发脑电波的时变最优滤波估计

本文提出了一个自修正的非平稳信号模型,并设计了时变最优滤波器于视觉诱发脑电波 的估计.估计出的信号与原始信号的各波峰潜伏期严格保持一致,而波峰幅值略有衰减.给 出的仿真与实体试验结果都证明了本方法的有效性.     

火力发电厂汽轮机叶片断落的分析

介绍了叶片断落的原因及预防方法,从检修和运行两方面,提出了防止叶片断裂的措施。     

小浪底水库坝前漏斗区泥沙测验分析

小浪底水库坝前漏斗区的形成和发展,直接影响到枢纽建筑物的安全运行。为了保持塔前“门前清,”掌握坝前漏斗区的形成和发展,保证水库进入拦沙后期和正常运用期的正常运用,对坝前漏斗区进行了泥沙测验分析。结果表明:目前漏斗区范围内纵向坡度较缓,尚没有明显的漏斗形成,仅在坝前和塔前200m×1000m范围形成了漏斗雏形。