M-Z外调制器最佳偏置点稳定控制

文章介绍了光通信用马赫-曾德(M-Z)外调制器的特点,说明了该调制器最佳偏置点控制的重要性,并对其转换函数及曲线进行了理论分析,推导出了最佳偏置点的特性及控制机理,提出并验证了最佳偏置点的控制技术和其实现方法.     

基于Kohonen神经网络的深度图像分割方法

提出一种基于Ｋｏｈｏｎｅｎ神经网络无监督的深度图像分割方法。首先计算了深度图像各点的导数,进而得到各点的法向,以法向和深度值作为每一点的特征矢量,引入自组织神经网络进行初始的聚类;为消除初始聚类产生的过分割现象,采取相邻表面片法向分析的方法进行再分割,得到最终的分割结果。本方法避免了通常的区域分割方法初始种子不易选取的弱点,聚类所用样本少,速度快。实验结果表现了算法良好的性能。     

Nanoparticles of the Lead-free Solder Alloy Sn-3.0Ag-0.5Cu with Large Melting Temperature Depression

Due to the toxicity of lead (Pb), Pb-containing solder alloys are being phased out from the electronics industry. This has lead to the development and implementation of lead-free solders. Being an environmentally compatible material, the lead-free Sn-3.0Ag-0.5Cu (wt.%) solder alloy is considered to be one of the most promising alternatives to replace the traditionally used Sn-Pb solders. This alloy composition possesses, however, some weaknesses, mainly as a result of its higher melting temperature compared with the Sn-Pb solders. A possible way to decrease the melting temperature of a solder alloy is to decrease the alloy particle size down to the nanometer range. The melting temperature of Sn-3.0Ag-0.5Cu lead-free solder alloy, both as bulk and nanoparticles, was investigated. The nanoparticles were manufactured using the self-developed consumable-electrode direct current arc (CDCA) technique. The melting temperature of the nanoparticles, with an average size of 30 nm, was found to be 213.9°C, which is approximately 10°C lower than that of the bulk alloy. The developed CDCA technique is therefore a promising method to manufacture nanometer-sized solder alloy particles with lower melting temperature compared with the bulk alloy.     

基于二维码技术的AFC系统研究与探讨

由于城市交通压力越来越大,城市轨道交通得到了迅速发展,同时越来越多的人选择乘坐地铁出行。传统的AFC系统主要以现金支付为主,排队买票浪费大量时间,乘客出行体验差,且需要大量现金,因此提出的二维码支付方式。二维码支付设计方案是在保持原有售检票机功能的基础上,增加使用移动设备二维码检票过闸功能。另外,详细说明了二维码支付的业务流程。二维码支付再地铁中的使用为地铁购票提供了便利,同时提高了地铁购票的效率和服务质量。     

Analysis of 3D NAND technologies and comparison between charge-trap-based and floating-gate-based flash devices

NAND flash chips have been innovated from two-dimension (2D) design which is based on planar NAND cells to three-dimension (3D) design which is based on vertical NAND cells. Two types of NAND flash technologies–charge-trap (CT) and floating-gate (FG) are presented in this paper to introduce NAND flash designs in detail. The physical characteristics of CT-based and FG-based 3D NAND flashes are analyzed. Moreover, the advantages and disadvantages of these two technologies in architecture, manufacture, interference and reliability are studied and compared.     

An opportunistic cooperation scheme and its BER analysis

The cooperative communication technology proposed in recent years enables network nodes to share their antennas to achieve diversity gain. In this paper, an efficient variation scheme on opportunistic cooperation is proposed by using an outage criterion, in which the cooperation mode will be adopted only when the channel from source to relay does not occur outage event. We derive a closed-form BER (bit error rate) expression for the proposed scheme over Rayleigh fading channels, showing that the full diversity is achieved by the new scheme. Also, the BER performance of the known coded cooperation is presented for the purpose of comparison with our scheme. Numerical results illustrate the superiority of the proposed scheme over the coded cooperation in terms of BER performance. It is pointed out that the corresponding BER advantage of the proposed scheme comes at the expense of increasing system overhead since the new scheme needs some feedback from relay to both source and destination.     

星载红外探测器组件环境适应性分析与性能优选

为满足低等级红外探测器组件在高可靠性领域的空间应用需求,对星载红外探测器组件进行温度循环试验、力学试验以及高温老炼试验等环境试验考核,并基于双积分球式均匀照明系统对环境试验前后红外探测器组件相对光谱响应率进行测试。通过对比环境试验前后红外探测器组件相对光谱响应率变化,分析红外探测器组件的环境适应性,揭示红外探测器组件的质量缺陷及其他潜在缺陷,剔除早期失效,并从参试红外探测器组件中筛选出性能优良的探测器应用在星载偏振扫面仪进行大气偏振探测。试验结果表明:参试的红外探测器组件在环境试验前后具有良好的稳定性和可靠性,可以满足航天载荷应用需求。     

Total Dose Radiation-Hard 0.8μm SOI CMOS Transistors and ASIC

介绍了采用全剂量SIMOX SOI材料制备的0．8μm SOI CMOS器件的抗总剂量辐射特性，该特性用器件的阈值电压、漏电流和专用集成电路的静态电流与高达500krad（Si）的总剂量的关系来表征．实验结果表明pMOS器件在关态下1Mrad（Si）辐射后最大阈值电压漂移小于320mV，nMOS器件在开态下1Mrad（Si）辐射后最大阈值电压漂移小于120mV，器件在总剂量1Mrad（Si）辐射后没有观察到明显漏电，在总剂量500krad（Si）辐射下专用集成电路的静态电流小于5pA．     

高温AlN为模板的AlGaN基p-i-n背照式日光盲探测器

第一次报道了以高温AlN为模板层的AlGaN基p-i-n背照式日光盲探测器的制作和器件特性.利用MOCVD方法在(0001)面的蓝宝石衬底上生长了探测器的AlxGa1-xN多层外延材料.在无需核化层的高温AlN模板上生长了p-i-n背照式日光盲探测器的无裂纹高Al组分(0.7)AlGaN多层外延结构.利用在线反射监测仪、三轴X射线衍射及原子力显微镜表征了外延材料的晶体质量.在1.8V的反向偏压下,制作的探测器表现出了日光盲响应特性,在270nm处最大响应度为0.0864A/W.具有约3.5V的正向开启电压,大于20V的反向击穿电压,在2V的反向偏压下暗电流小于20pA.     

低频UWB SAR的冲击响应函数

提取系统的冲击响应函数(impulse response function,IRF)是测量雷达系统性能指标的前提,IRF来自理想点目标的雷达图像。对于低频超宽带合成孔径雷达(ultra wide band synthetic aperture radar,UWB SAR),参考点目标的电磁散射特性是频率和方位角的函数,不满足理想点目标的散射特性要求。本文从IRF的定义出发,结合低频UWBSAR系统处理模型,利用二维数字聚焦方法消除杂波的影响,同时利用低频电磁散射数值建模的方法计算参考点目标的电磁散射特性,最后给出了计算系统IRF的方法。