网络时延对数据中心布局的影响研究

随着5G、移动互联网、大数据、人工智能等信息技术与经济社会各领域的深度融合,不同业务数据对传输时延提出了不同要求,低时延业务需求迅速增长,网络时延已成为用户选取数据中心的重要指标。在端到端分析数据包传输的基础上,重点研究了影响网络时延的主要因素及相应的优化措施,并提出数据中心选址的建议。     

新型5G智慧园区建设的探索与研究

近年来我国园区转型步伐加快,各地纷纷开展了智慧园区建设。以5G为引领的新一代信息技术引发了新一轮的智慧园区建设。通过对智慧园区的发展现状及趋势进行分析,结合5G智慧园区的需求和目标,以某视频产业园区为例,阐述了新型5G智慧园区建设策略建议,以顶层设计为引领,构建信息基础设施,以园区智能运营管理平台(IOC)为核心,助力产业升级与园区管理。     

银键合丝力学性能对键合质量的影响

通过调节微合金元素的含量获得3种具有不同力学性能的银键合丝.利用拉伸试验、键合试验、焊线挑断力、焊球推力测试等手段,研究了银键合丝力学性能对键合质量的影响.结果表明,在延伸率相同的条件下,随着微合金元素含量的降低,3种键合丝的断裂负荷降低,初始模量先减小后增大,键合后焊线挑断力和焊球推力均降低,电极金挤出率先减小后增大.银键合丝初始模量较低时在超声和压力的作用下易于变形,焊线内残余应力较低且第二焊点与引线框架结合较好,因此挑断测试时第二焊点与框架材料界面处不易发生脱离,有利于获得更高的键合成功率.     

不同插入层对抑制Mg掺杂p-GaN的记忆效应

研究了低温(LT) GaN和AlN不同插入层对抑制Mg掺杂p-GaN金属有机化学气相沉积外延中存在的记忆效应的影响,外延生长p-GaN缓冲层,制作具有该缓冲层的AlGaN/GaN高电子迁移率晶体管(HEMT),并对该器件进行电学测试.二次离子质谱仪测试表明p-GaN上10 nm厚的LT-GaN插入层相比于2 nm厚的AlN插入层能更好地抑制Mg扩散.霍尔测试表明,2 nm厚的AlN插入层的引入和GaN存在较大的晶格失配会引入位错,进而会降低AlGaN/GaNHEMT的电子迁移率以及增加其方块电阻;含有10 nm厚的LT-GaN插入层的p-GaN作为缓冲层的AlGaN/GaN HEMT,其方块电阻、电子迁移率以及二维电子气(2DEG)密度分别为334.9 Ω/口,1 923 cm2/(V·s)和9.68×1012 cm-2.器件具有很好的直流特性,其饱和电流为470 mA/mm,峰值跨导为57.7 mS/mm,电流开关比为3.13×109.     

Energy‐Dissipative Matrices Enable Synergistic Toughening in Fiber Reinforced Soft Composites

Tough hydrogels have shown strong potential as structural biomaterials. These hydrogels alone, however, possess limited mechanical properties (such as low modulus) when compared to some load‐bearing tissues, e.g., ligaments and tendons. Developing both strong and tough soft materials is still a challenge. To overcome this obstacle, a new material design strategy has been recently introduced by combining tough hydrogels with woven fiber fabric to create fiber reinforced soft composites (FRSCs). The new FRSCs exhibit extremely high toughness and tensile properties, far superior to those of the neat components, indicating a synergistic effect. Here, focus is on understanding the role of energy dissipation of the soft matrix in the synergistic toughening of FRSCs. By selecting a range of soft matrix materials, from tough hydrogels to weak hydrogels and even a commercially available elastomer, the toughness of the matrix is determined to play a critical role in achieving extremely tough FRSCs. This work provides a good guide toward the universal design of soft composites with extraordinary fracture resistance capacity.     

Highly Conductive Transition Metal Carbide/Carbonitride(MXene)@polystyrene Nanocomposites Fabricated by Electrostatic Assembly for Highly Efficient Electromagnetic Interference Shielding

Highly conductive polymer nanocomposites are greatly desired for electromagnetic interference (EMI) shielding applications. Although transition metal carbide/carbonitride (MXene) has shown its huge potential for producing highly conductive films and bulk materials, it still remains a great challenge to fabricate extremely conductive polymer nanocomposites with outstanding EMI shielding performance at minimal amounts of MXenes. Herein, an electrostatic assembly approach for fabricating highly conductive MXene@polystyrene nanocomposites by electrostatic assembling of negative MXene nanosheets on positive polystyrene microspheres is demonstrated, followed by compression molding. Thanks to the high conductivity of MXenes and their highly efficient conducting network within polystyrene matrix, the resultant nanocomposites exhibit not only a low percolation threshold of 0.26 vol% but also a superb conductivity of 1081 S m^?1 and an outstanding EMI shielding performance of >54 dB over the whole X‐band with a maximum of 62 dB at the low MXene loading of 1.90 vol%, which are among the best performances for electrically conductive polymer nanocomposites by far. Moreover, the same nanocomposite has a highly enhanced storage modulus, 54% and 56% higher than those of neat polystyrene and conventional MXene@polystyrene nanocomposite, respectively. This work provides a novel methodology to produce highly conductive polymer nanocomposites for highly efficient EMI shielding applications.     

基于Android嵌入式系统的密立根油滴实验智能仪器

针对传统密立根油滴实验仪器仪计算不方便、辅助计算工具所占空间大等缺点,利用ARM9嵌入式开发平台,结合嵌入式Android的优势,研究并设计用于高校进行密立根油滴实验的智能实验仪器.完成了智能仪器的硬件设计,并开发出基于嵌入式Android的实验软件.实际运行结果表明,该智能实验仪器整体性能良好,触摸屏为用户提供友善的人机交互界面,辅助计算软件使数据处理更加方便.本仪器具有高可拓展性和高集成性的特点,极大的减少了实验中冗余的外部设备,实现实验智能化.     

基于PSD的光轴平行性测试装置电路系统

为了能够实现对车载观瞄系统光轴平行性的高精度测量,利用PSD捕捉微弱光信号来获取光斑的空间位置坐标,对该电路系统主要从信号处理电路部分和延时电路部分进行分析和设计.首先,在分析PSD基本工作原理的基础上,设计其信号处理电路部分和延时电路部分,实现激光三轴的光轴平行性检测.然后,结合误差理论,分析电路系统的测量误差和精度.结果表明:选择位置分辨率为1.5μm的S1880型PSD时,其测量精度能够达到±1.7407".     

宽带CARS技术用于气体温度的测量

本文报道了用宽带CARS技术测量高温空气的温度及其实时的升降过程。结果明显地优于有滞后效应的常规热电偶测试方法。     

Highly stable strained layer leaky-mode diode laser arrays

A simple fabrication process for InGaAs strained quantum well leaky-mode laser arrays is demonstrated. The arrays are ten-element devices grown by two-step metal-organic chemical vapor deposition. The structure consists of a strained quantum well InGaAs graded index-separate confinement active region and a thin (0.12 μm), transparent GaAs waveguide region. The near-field pattern typical of leaky-mode phase-locked arrays was measured. Fundamental mode oscillation was observed up to 2 A (threshold was as low as 175 mA). The authors observed a 1 μs pulsed optical output power of 172 mW per facet and a far-field angle (full width at half maximum) of 1.6 times the diffraction limit at 1 A. This is the first reported operation of a strained quantum well leaky-mode laser utilizing a built-in index step