Performance analysis of nonorthogonal multiple access‐based underlay cognitive relay network

This paper considers cooperative non‐orthogonal multiple access (NOMA) scheme in an underlay cognitive radio (CR) network. A single‐cell downlink cooperative NOMA system has been considered for the secondary network, consisting of a base station (BS) and two secondary users, ie, a far user and a near user. The BS employs NOMA signaling to send messages for the two secondary users where the near user is enabled to act as a half‐duplex decode‐and‐forward (DF) relay for the far user. We derive exact expressions for the outage probability experienced by both the users and the outage probability of the secondary system assuming the links to experience independent, nonidentically distributed Rayleigh fading. Further, we analyze the ergodic rates of both the users and the ergodic sum rate of the secondary network. The maximum transmit power constraint of the secondary nodes and the tolerable interference power constraint at the primary receiver are considered for the analysis. Further, the interference caused by the primary transmitter (PT) on the secondary network is also considered for the analysis. The performance of the proposed CR NOMA network has been observed to be significantly better than a CR network that uses conventional orthogonal multiple access (OMA) scheme. The analytical results are validated by extensive simulation studies.     

新型可彩色化液晶显示技术应用

从技术原理分析、实例对比、软硬件分析设计等方面,深入浅出地介绍一种新型可彩色化显示技术,可应用于升级传统黑白显示液晶屏,具有性价比及兼容性等方面的优势,对于彩色化应用有一定的参考价值。     

全断面混凝土衬砌钢模台车的应用

羊湖电站引水隧洞总长５８８３ｍ,为φ２．５ｍ的圆形有压隧洞,全线采用钢筋混凝土衬砌。施工区空气稀薄,严重缺氧,气候寒冷。混凝土衬砌采用φ２．５ｍ全断面钢模台车进行,混凝土由洞外拌和系统拌和,有轨运输进洞,混凝土泵送入仓。全断面钢模台车由钢模、台车和外部支撑三部份组成,钢模的构成方式为“三铰两缝式”。本文介绍了羊湖水站引水隧洞混凝土衬砌中应用φ２．５ｍ全断面钢模台车的使用情况和施工方法。     

The location of hydrogen in the kinetics of oxidation of ferrous alloys by superheated steam

The rate of emission of hydrogen from the metal surface and from the oxide surface has been determined during the oxidation of ferrous alloys at 501°C. The kinetics were in accordance with the assumption of a parabolic rate law, and the rate constants were in agreement with those calculated from the thickness of the oxide layer at the end of the reaction. The proportion of hydrogen emitted from the metal to that from the oxide surface showed a dependence on the partial pressure of steam for the 9%Cr-1%Mo alloy at 501°C. The ratio was dependent on the alloy composition, and also on temperature, as shown by results for the 9%Cr-1%Mo alloy at 450 and 552°C. For this alloy, the activation energy and rate constants are consistent with a rate-determining step dependent on cation diffusion. The oxide film is almost impermeable to hydrogen gas. A possible oxidation mechanism is suggested.     

Intranet非法站点及不良信息检测系统的设计与实现

现在越来越多的企事业单位和政府部门均建立了自己的Intranet,局域网上的信息管理越来越成为各单位领 导和信息安全管理人员的课题。本文提出了一个整合网络蜘蛛、文档分类和全文搜索技术的系统,通过试验证明了该系 统可以有效地对Intranet信息进行监控和管理。     

基于深度卷积神经网络的自适应图像去雾算法

室外拍摄图像由于受雾气、雾霾、沙尘等大气颗粒杂质的影响呈现出图像灰白化,而现有的图像去雾算法存在过度依赖先验信息、透射率计算不精确的问题。针对上述问题,文中提出了一种基于深度卷积神经网络的自适应图像去雾算法。该算法基于大气散射模型实现了有雾图像的去雾,设计浅层提取、并行提取和深度融合共3个全卷积网络实现图像浅层特征与深层特征的融合,大幅提高了透射率图的准确性。去雾实验测试结果表明,文中所提出的算法对室外露天雾图具有良好的去雾效果,且去雾细节效果更加理想。     

喷墨打印技术在PCB中的应用前景

文章简要的介绍了喷墨打印技术在PCB工业中的应用前景。从喷墨打印技术在PCB中应用发展来看,首先是在图形转移中应用,然后再推广应用到埋嵌无源元件和全印刷电子产品的的领域上。今后,喷墨打印技术会成为PCB工业生产的主流之一。     

大幅面太阳全光谱辐照系统的设计

大幅面太阳全光谱辐照系统是太阳模拟器的重要组成部分,辐照不均匀度是其关键技术指标之一,在传统全光谱辐照系统中存在着难以达到国家标准、光源光谱匹配性差等技术难题。结合大幅面太阳模拟器的研究现状,设计了一种全光谱辐照系统。利用光学仿真软件Zemax对所设计的全光谱辐照系统辐照均匀性进行仿真,提出了辐照度衰减模式的新概念,并以此为基础对全光谱辐照系统辐照不均匀度进行了优化。光源采用瑞士Solaronix公司生产的Plasma光源,经过测试光谱达到国际电工委员会标准A级,光源谱段内辐照度用光谱辐射计进行测试。结果表明,在辐照度为280 W/m²时,辐照度衰减模式在未启动和启动时辐照不均匀度分别为8.4%和5.7%,参考国家标准GB/T12637—1990太阳模拟器通用规范,在2 400 mm×6 000 mm有效辐照面内其辐照均匀度满足规范C级标准,接近B级标准。     

化学成分对ASTMA890双相不锈钢组织的影响

研究化学成分对ASTM A890双相不锈钢组织的影响,利用金相显微镜对试样进行组织观察,结合体视学定量金相,利用最小二乘法对所测得数据进行拟合,建立双相不锈钢的组织及相比例与化学成分之间的直接联系。结果表明:铬当量Creq=26.68%、镍当量Nieq=11.89%时,可使双相不锈钢的相比例达到理想的1∶1,从而获得良好的综合性能。