典型微区环境下信道特性的仿真结果

多径效应产生的扩散效应一直是无线信道研究的主要问题。作者利用自行开发的无线信道仿真软件对微区环境下的主要信道特性进行了大量的仿真，得到了典型微区环境下的传播损耗，时延扩展和角度扩散等主要信道特性的描述。     

椭圆介质柱光子晶体导模区域的调控

利用时域有限差分方法,理论研究了由介电常数为8.9的介质柱排列在空气背景中组成的二维正方晶格光子晶体耦合腔光波导的传输特性.理论模拟结果表明,将微腔紧邻的两个圆形介质柱改变为椭圆形.通过改变椭圆的旋转角度能够调控导模的频率范围.通过将相邻微腔两边的椭圆形设置为不同旋转角度,可以在保证高传输效率的同时进一步地降低导模的群...     

基于低秩表示的鲁棒判别特征子空间学习模型

特征子空间学习是图像识别及分类任务的关键技术之一,传统的特征子空间学习模型面临两个主要的问题。一方面是如何使样本在投影到特征空间后有效地保持其局部结构和判别性。另一方面是当样本含噪时传统学习模型所发生的失效问题。针对上述两个问题,该文提出一种基于低秩表示(LRR)的判别特征子空间学习模型,该模型的主要贡献包括：通过低秩表示探究样本的局部结构,并利用表示系数作为样本在投影空间的相似性约束,使投影子空间能够更好地保持样本的局部近邻关系;为提高模型的抗噪能力,构造了一种利用低秩重构样本的判别特征学习约束项,同时增强模型的判别性和鲁棒性;设计了一种基于交替优化技术的迭代数值求解方案来保证算法的收敛性。该文在多个视觉数据集上进行分类任务的对比实验,实验结果表明所提算法在分类准确度和鲁棒性方面均优于传统特征学习方法。

     

InP-based enhancement-mode pseudomorphic HEMT with strainedIn0.45Al0.55As barrier andIn0.75Ga0.25As channel layers

Using strained aluminum-rich In_0.45Al_0.55As as Schottky contact materials to enhance the barrier height and indium-rich In_0.75Ga_0.25As as channel material to enhance the channel performance, we have developed InP-based enhancement-mode pseudomorphic InAlAs/InGaAs high electron mobility transistors (E-PHEMT's) with threshold voltage of about 170 mv. A maximum extrinsic transconductance of 675 mS/mm and output conductance of 15 mS/mm are measured respectively at room temperature for 1 μm-gate-length devices, with an associated maximum drain current density of 420 mA/mm at gate voltage of 0.9 V. The devices also show excellent rf performance with cutoff frequency of 55 GHz and maximum oscillation frequency of 62 GHz. To the best of the authors' knowledge, this is the first time that InP-based E-PHEMT's with strained InAlAs barrier layer have been demonstrated     

网络管理体系结构立体模型及其应用的研究

给出了网络管理体系结构的定义及其要研究的问题,在TMN逻辑分层体系结构的基础上,提出网络管理体系结构立体模型并具体研究了它在基于ATM网络的VPN业务管理中的应用。     

1.5mm腔长InAs/InP量子点激光器镜面外腔光谱特性研究

基于研制的1.5mm腔长InAs/InP共面条状量子点激光器,搭建了其镜面外腔结构,并对其光谱特性进行了测试,获得了镜面外腔周期性调制光谱,并在周期性的产生、多模激射和模式随电流的变化等方面对其光谱特性进行了分析研究。相比以前为获得单模使用的超短腔长超短外腔量子阱激光器,长腔长InAs/InP量子点激光器表现出较小的模式压缩比,更容易发生多模激射。     

全数字光PPM接收机的最佳帧节同步

光ＰＰＭ通信有良好的应用前景,同步是它实现的核心问题,本文推导了全数字光ＰＰＭ接收机的最大似然帧节同步算法,并给出了两个更容易实现的简化算法,讨论了最佳ＰＰＭ同步序列的设计问题,用计算机模拟了三种算法的工作性能。     

光纤电流传感器研究新进展

介绍了全光纤电流传感器自１９９４ 年以来在光纤处理技术、新光路设计、新材料光纤、新结构光纤及对系统性能的专项研究方面取得的新进展。     

Review of roll-to-roll fabrication techniques for colloidal quantum dot solar cells

Colloidal quantum dots (CQDs) are of great interest to photovoltaic (PV) technologies as they possess the benefits of solution-processability, size-tunability, and roll-to-roll manufacturability, as well as unique capabilities to harvest near-infrared (NIR) radiation. During the last decade, lab-scale CQD solar cells have achieved rapid improvement in the power conversion efficiency (PCE) from ~1% to 18%, which will potentially exceed 20% in the next few years and approach the performance of other PV technologies, such as perovskite solar cells and organic solar cells. In the meanwhile, CQD solar cells exhibit long lifetimes either under shelf storage or continuous operation, making them highly attractive to industry. However, in order to meet the industrial requirements, mass production techniques are necessary to scale up the fabrication of those lab devices into large-area PV modules, such as roll-to-toll coating. This paper reviews the recent developments of large-area CQD solar cells with a focus on various fabrication methods and their principles. It covers the progress of typical large-area coating techniques, including spray coating, blade coating, dip coating, and slot-die coating. It also discusses next steps and new strategies to accomplish the ultimate goal of the low-cost large-area fabrication of CQD solar cells and emphasizes how artificial intelligence or machine learning could facilitate the developments of CQD solar cell research.     

帧中继交换技术

本文论述了帧中继交换的概念、标准，结构、特点网络式样及在互连网中的应用。