锥形图形衬底上氮化镓薄膜生长和表征

GaN films are grown on cone-shaped patterned sapphire substrates(CPSSs)by metal-organic chemical vapor deposition,and the influence of the temperature during the middle stage of GaN growth on the threading dislocation(TD)density of GaN is investigated.High-resolution X-ray diffraction(XRD)and cathodeluminescence(CL)wereusedtocharacterizetheGaNfilms.TheXRDresultsshowedthattheedge-typedislocation density of GaN grown on CPSS is remarkably reduced compared to that of GaN grown on conventional sapphire substrates(CSSs).Furthermore,whenthegrowthtemperatureinthemiddlestageofGaNgrownonCPSSdecreases,the full width at half maximum of the asymmetry(102)plane of GaN is reduced.This reduction is attributed to the enhancement of vertical growth in the middle stage with a more triangular-like shape and the bending of TDs.The CL intensity spatial mapping results also showed the superior optical properties of GaN grown on CPSS to those of GaN on CSS,and that the density of dark spots of GaN grown on CPSS induced by nonradiative recombination is reduced when the growth temperature in the middle stage decreases.     

超高斯脉冲反饱和吸收效应响应特性理论模拟

基于非线性传输方程与五能级速率方程的耦合模型分析了超高斯脉冲在反饱和吸收(RSA)作用下的动态响应特性。研究了脉冲时空波形在RSA材料中的演化规律以及脉冲与材料相互作用的动力学过程。讨论了单重态第一激发态寿命对输出脉冲时空波形的影响,并优化了材料参数以避免时空畸变。对新型RSA材料的开发以及在时空波形敏感领域的应用具有指导意义。     

方位多通道合成孔径雷达数据重建方法

多通道合成孔径雷达可以突破传统SAR不能同时实现高分辨宽测绘带的限制,是SAR发展的必然趋势,在成像处理时,它必须重建方位均匀采样数据。该文提出了一种基于降升调频斜率技术的处理方法,利用线性调频信号特性对方位非均匀数据进行解线性调频处理,然后采用升采样参考函数进行逆解线性调频处理,即完成方位数据的均匀重建。文中给出了信号处理流程,并与重建滤波器组法进行了比较。仿真结果证明了理论分析的正确性。     

LTE协议解决方案及系统实现

介绍了LTE特点及现状.协议测试及重要性根现状给出了LTE协议测试解决方案并通过安立公司的MD8430A基站仿真器和MD8435A终端仿真器外加两台控制PC搭建测试平台,在平台上成功实现了LTE终端从搜索注册网络建立连接信令流程及数据传输物理层仿真.仿真速率上行达到50Mbit/s下行100Mbit/s的高速率传输,给出了各流程源程序,对于LTE移动终端的研发具有重要的作用.     

A review:Photonics devices,architectures,and algorithms for optical neural computing

The explosive growth of data and information has motivated various emerging non-von Neumann computational approaches in the More-than-Moore era.Photonics neuromorphic computing has attracted lots of attention due to the fascinating advantages such as high speed,wide bandwidth,and massive parallelism.Here,we offer a review on the optical neural computing in our research groups at the device and system levels.The photonics neuron and photonics synapse plasticity are presented.In addition,we introduce several optical neural computing architectures and algorithms including photonic spiking neural network,photonic convolutional neural network,photonic matrix computation,photonic reservoir computing,and photonic reinforcement learning.Finally,we summarize the major challenges faced by photonic neuromorphic computing,and propose promising solutions and perspectives.     

Word-Representation-Based Method for Extracting Organizational Events from Online Media

Online social media exhibit massive organizational event relevant messages, and the well categorized event information can be useful in many real-world applications. In this paper, we propose a research framework to extract high quality event information from massive online media data. The main contributions lie in two aspects: First, we present an event-extraction and event-categorization system for online media data; second, we present a novel approach for both discovering important event categories and classifying extracted events based on word representation and clustering model. Experimental results with real dataset show that the proposed framework is effective to extract high quality event information.     

流媒体数据在EGPRS无线接口中的传输问题研究

分析基于EGPRS网络的流媒体传输系统。因为流媒体数据在下行链路上的传输性能取决于系统对无线接口协议中RLC/MAC模块的配置与实现,所以重点研究了实现RLC/MAC协议的技术,如选择性检错重发技术。     

The magic of split augmented Lagrangians applied to K-frame-based l 0–l 2 minimization image restoration

We propose a simple, yet efficient image deconvolution approach, which is formulated as a complementary K-frame-based l ₀–l ₂ minimization problem, aiming at benefiting from the advantages of each frame. The problem is solved by borrowing the idea of alternating split augmented Lagrangians. The experimental results demonstrate that our approach has achieved competitive performance among state-of-the-art methods.     

驻极体空气过滤材料消静电实验研究

选取4片不同级别的驻极体空气过滤材料,对滤料消除静电效应前后的计数效率和PM2.5净化效率等性能参数进行了试验研究,消静电方法采用的是异丙醇浸泡法,试验用气溶胶为KCl固态气溶胶。试验结果表明:采用异丙醇浸泡法能够在一定程度上消除驻极体过滤材料本身所带的静电;消除静电效应后滤料对不同粒径颗粒的计数效率均有所下降,特别是颗粒物粒径越小,过滤效率下降的幅度也越大;消静电后滤料对PM2.5的净化效率也有所下降。研究结果揭示了采用驻极体过滤材料制造而成的带静电过滤器在实际使用过程中可能存在的因静电消失后带来的效率下降风险,试验数据也能为将来空气过滤器国家相关标准的修订提供参考建议。     

Charge： Glowing in the Dark

Many areas of structure analysis have focused on finding the locations of the atoms. If, instead of the atoms, we knew the positions of the electrons we would in fact know much more, and in most respects knowing where the nuclei are is not important. There is a long history of measurements using precise electron diffraction or X-ray diffraction of the average charge density in materials, but extending beyond to local charge density is, as yet, an unexplored area.